Battery Performance of Apple Watch in a Marathon

On Sunday, October 13, I ran the 2019 Chicago Marathon with an Apple Watch Series 5. This is a quick report on how well the watch battery performed.

TL;DR: Apple Watch Series 5 used only 50% battery over a full marathon distance, ran in 3:53:25.

⚡️ 50%   ⏱ 3:53:25   🏃‍♂️ 26.2 miles

Apple Watch Setup

  • Series 5, 40mm in Titanium, with ‪watchOS 6.0.1‬
  • Untethered — ran without tethered iPhone
  • Cellular was Off
  • Theater Mode was On‬
  • Used the Workout app to track the run
  • Power Saving Mode for the Workout app was Off
  • No streaming audio — no music or podcast was played
  • Water Lock was On

Total Run Duration

  • 3 hours, 53 minutes, and 25 seconds

Total Run Distance

  • 26.2 miles
  • Distance tracked by the Workout app: 26.91 miles (See Notes below)

Battery Used: 50%

  • Only 50% battery was used to run a full marathon
  • 96% charge before start
  • 46% charge at the finish
Battery at 96% before start

Battery at 96% before start

Battery at 46% after finish

Battery at 46% after finish


  • [7:15 AM] Kept the watch powered down until 15 minutes before the race officially started.
  • [7:18 AM] On startup, battery was at 99%, I tapped on the Weather complication to refresh. That seemed to take too long (couple of minutes), so I immediately turned off WiFi and Cellular. Battery was now at 97%, probably from the network call trying to refresh weather.
  • [7:20 AM] Turned On theater mode about 10 minutes before the race started. Bad idea, because it got tricky to wake up the watch display and start a workout with gloves on. Yes, that was me standing past the start line to start a workout 🤪. I usually put it in theater mode after starting a run. Never go off script during a race.
  • [7:45 AM] I crossed the start line at 15 minutes past official start time. About 45K runners run the Chicago marathon every year, so the race is started in waves with different corrals of runners.
  • [7:45 AM] The watch had been on now for about 30 minutes, and in theater mode for about 25 minutes, at 96%.
  • With Power Saving Mode for the Workout app disabled, Apple Watch tracked the heart rate with the built-in sensor through out the run. But with Theater Mode On and Cellular Off, it essentially utilized 2 out of the 3 techniques that the Workout app's Power Saving Mode uses.
  • Turning Theater Mode On disabled always-on display, and required tapping the screen everytime I wanted to view my running data (pace, distance, etc) in progress. I am used to this, because I have been using the same setup during my long runs for the past year, with Apple Watch Series 4.
  • Workout app reported final distance to be 26.91 miles vs the official 26.2 miles. The additional distance of 0.71 miles is pretty normal for most of the tracking devices at such long-distance races due to reasons like erratic GPS signal around tall city buildings, or turns and curves adding up.

Marathon Ready

I have been training for and running marathons with Apple Watch since it launched in 2015. In total, I have run 6 marathons with Apple Watch(es), at least one marathon with every year’s model. There is no question on how well can the Apple Watch handle marathon training and racing. With only 50% battery utilization for an almost 4-hour marathon run, Apple Watch is an extremely versatile and powerful fitness device that no runner should ignore.

Here’s my marathon run in Tempo


2.6.2: A Tribute to the Marathon Distance

If you want to run, run a mile. If you want to experience a different life, run a marathon.

— Emil Zátopek

For many runners, the marathon distance is sacred. To run a marathon, we can't fake through the training, and even when the training buildup goes perfectly, anything can happen on race day. A subtle variation from our plan on race day can have magnifying disastrous effects on our performance and experience. A lot of such critical variables are not even in our control to begin with. Running a marathon is a journey that changes us in so many ways. It’s such a unique lifetime experience that many of us find ourselves allured by the numbers 26.2 and 13.1 — the full and half marathon distance in miles.

iOS 13.1 instantly brought out the above intrigue in me. Without any specific plan around the release numbers, Tempo ended up being at 2.6.0 for iOS 13.0 launch. As iOS quickly went to 13.1, and Tempo was just .2 shy of 2.6.2, it felt like meant to be to ignore. So as a tribute to the marathon distance, Tempo has been updated to version 2.6.2 for iOS 13.1.✨

I wanted to do something simple and quick, but special for this one, so I picked up another version of dark mode theme. It was scrapped in favor of what we currently have as the default dark mode. After spending some time on it, to my surprise, the result is a beautiful new theme that we are calling Deep Blue. The name is still tentative for this one, we considered Blue Medal, Endurance Blue, Magic Blue, but for now Deep Blue it is. Please feel free to send your suggestions for the name.

There are also a couple of important bug fixes and enhancements, but I am really glad that we got this beautiful new dark mode theme in Deep Blue for this release. The fact that the theme was almost scrapped makes it special in its own way.

Dark Mode

Happy iOS 13 release day! iOS 13 brings the beautiful new dark mode, and Tempo is ready to sport the new look on day one. Tempo looks gorgeous and vibrant in dark mode.

Quick confession time: I do not use dark mode on my mac, so I was not too sure how it would work out on iOS. But as I was implementing it for Tempo, it slowly grew on me. Now I am a convert, so much so that I implemented a dark mode override feature in Tempo. While Tempo can match the system level dark mode (on/off) preference, with the override feature, it can also be enabled in dark mode while leaving the dark mode off at the system level.

You can start using Tempo in dark mode today by updating to v2.6.0 with iOS 13. Enjoy!

Tempo on 9to5Mac Watch Time

Zac Hall invited me to talk about the origin story of Tempo (and how it led me to go full-time indie) on his 9to5Mac Watch Time podcast series.

When Zac asked if I would be interested in doing this, the introvert in me instantly wanted to find an excuse to politely say no and get out of it. This was my first podcast ever, and I was nervous, but I agreed because being indie is also about sharing the story and inspiration. Zac is a great host, and carried me through the conversation. Sorry, if I rambled too much, Zac. I am glad I got to do this, because story telling in audio format is so different than a blog, and I really enjoyed it.

My thanks to Zac for having me on the show, and including Tempo with all the inspiring stories on Watch Time. Thank you to all the listeners who have reached out and sent words of encouragement.

9to5Mac Watch Time podcast episode 6: Making apps for Apple Watch with Rahul Matta and Will Bishop

Cadence for Runners

Tempo v2.5.0 makes it easy for runners to analyze cadence data.

Cadence, also known as stride rate, is number of steps taken per minute (SPM). It is measured by counting number of times both the feet hit the ground in a minute. Back in the day, measuring cadence was a manual task done by counting number of times one of the feet hit the ground in a minute and multiplying that number by 2. These days, most running watches display live cadence on our wrist during a run.

If you think about it, at a very basic level, running pace (speed) is the byproduct of how fast the feet move (cadence) and how far they move with each step (stride length).

Pace = Cadence x Stride Length

So generally speaking, faster cadence would mean faster pace. That's easier said than done due to physical and physiological condition and limitations of our bodies.

In his book Daniels' Running Formula, legendary running coach Jack Daniels describes ideal cadence to be 180 SPM. He derived this number by observing runners compete from 800 meters all the way up to the marathon distance at the 1984 Olympics.

Apple Watch started supporting live cadence in the Workout app with watchOS 5.0. Doing some quick analysis of my past data, it looks like there is cadence data saved by the Workout app from pre-watchOS 5.0 versions as well. But the older cadence data was sampled at around 10 mins intervals vs every few seconds in the latest version.

Good news is that all this data is also saved and available in the Health app for us to analyze. So with v2.5.0, Tempo now supports a detailed view of cadence data. You can view your cadence (along with pace and heart rate) for every split, and interact with a timeline of your cadence tracked over the entire run on a graph. I have wanted this feature for a while now, and I am not alone; there have been a lot of runners who have made this feature request. And it looks like there are even more runners out there, waiting on other running apps to support it. Please do give Tempo a try while you are waiting :)

There's a lot more information about why cadence matters, how to improve it, and different coaches' advice and opinions on the topic. You should really first study your own data, learn more about cadence, maybe get some pro help, before experimenting to use cadence as the next make me faster trick.

Disclaimer: please do not take any of this information as running advice or coaching guidance. The data in Tempo is from your Apple Watch and should be accurate (unless otherwise due to software bugs). My explanation of cadence above is my understanding from reading various posts and books about running, and from my general training experience. Your mileage may vary.

Going Indie

To give anything less than your best, is to sacrifice the gift.

— Steve Prefontaine

On July 31, 2019, I left my full-time job as a software engineer. It paid well, and I got to work with some talented folks on an interesting product, but it wasn’t something that I have been wanting to pursue next. So as crazy as it sounds, and I am still uncomfortable about it, I have taken the first step towards that next. It’s ambitious, exciting, and nerve-racking. The general idea is to build things independently, of high quality, with strong ethics, what feels right, and make that into a sustainable indie software business.

I have no clue if that is doable. I could crash and burn in 12-18 months, but let’s not digress too far. For now I do not want to think about plan B, but focus on what I can do to build a successful indie business.

Where do we start? I have had this side project called Tempo. Tempo is a fantastic app for runners. Runners love it. It has 3 years of slow-paced, but solid development under it, and a bunch of paying customers. I believe it has a lot of potential for various reasons. And it converges my love for running with the craft of building products into one. So that’s where we are going to start.

There's a solid roadmap for Tempo that I am starting with. A lot of it is based on feedback and feature requests from real runners over the past 3 years. My focus here is going to be simple, and based on the same core principle that Tempo was built with: build the best app for runners, with strong emphasis on privacy and quality design. Do that at a healthy pace, make constant progress, and keep shipping, while paying careful attention to revenue and growth.

That’s my general indie plan, my next adventure.

I can really use all the help I can get. If you would like to help, here are some ideas,

  • If you run with an Apple Watch, please download Tempo and subscribe. And if you don’t find Tempo good enough yet, please reach out, and let me know how I can make it better for you to subscribe.

  • If you do any kind of app reviews or publishing, please write about Tempo. Again, if it’s not there yet, please let me know what would make Tempo worthy of your time.

  • Help spread the word by telling your running friends and family about Tempo. You can share it easily by suggesting to checkout

  • If you are an indie developer, let’s connect. I would love to learn as much as I can about making this work.

You can find me on twitter @rmatta, or email

My Thanks to the Founding Users

When Tempo 2.0 was launched, the early adopters got 2 free years of Tempo Premium. I wrote the following note to them. It will be visible to all the founding users in v2.4.0 of Tempo. But I also wanted to express my gratitude more openly, so here’s a copy of it.

Dear Fellow Runner,

Did you know that you are one of the founding users of Tempo? Every runner, who originally paid to download v1.0 of Tempo from the App Store, is a Founding User. I wanted to take a moment and thank you.


Thank you for being a Founding User.

It’s been 3 years, and we have come a long way since the initial launch. Tempo's version 2 introduced pro features with premium subscription. Runners have loved pro features like route maps, simple graphs, tags, trends, and more.


Tempo v2.0 introduced pro features
with premium subscription.

Your patronage, as a founding user, was extremely motivating for me to keep working on Tempo. As a token of my gratitude, Tempo premium, with all the pro features, was free for you for the first 2 years, until August 15, 2019.


Tempo premium was free for you
for the first 2 years.

I hope you have found Tempo effective in your training journey so far, and will continue your support by subscribing to premium going forward. As you know, Tempo was built and has always focussed on the core principles of privacy and great design. We respect your privacy without any fine prints or caveats, and we sweat the details to create a simple and beautiful experience to visualize powerful insights to help us run better. I strongly believe that Tempo is the best value compared to any other running app out there today, but we are also not done yet, and making it better every day.


Goal is to be the best app for runners.

Finally, I wanted to share some personal, but relevant, recent news – I have officially switched to working on Tempo full-time. Over the past 3 years, Tempo has been work of passion that I have enjoyed deeply, both as a craft and as a way to build something for my fellow runners. It’s been a lot of late evenings and weekend hours, balancing with family and running. My goal for Tempo has always been to make it the best app for runners. And now I am dedicating my full energy to pursue that goal. Your premium subscription will further enable that pursuit for me, and more importantly for our running community!


Your premium subscription will enable
Tempo to be the best.

Thank you & Keep Running!


Tempo 2.0

I am ecstatic to be launching 2.0 of Tempo. While it took way longer than I anticipated, I have enjoyed building it. It’s a labor of love and a lot of running, testing, and throwing away work that I didn’t find good. And it’s looking fantastic! I have said this before, but it needs emphasis again,

Tempo is my daily go to app. I do not run every day, but I use Tempo every day, multiple times on some days, to stay motivated. It provides great insights to help improve and optimize my running.

I can go on detailing every feature here, but instead I will just mention a recent scenario that made me disappointed and smile at the same time. Disappointed because I should have known better after all these years of training and it’s so obvious in retrospect; smile because Tempo revealed it for me: Just a few weeks ago, as I was scrolling through one of the new screens, called Intensity Log, I discovered why I might have crashed so badly during my last marathon. There was an obvious training strain pattern during the last few weeks leading up to the race. Those weeks are meant for recovering/tapering to peak for race performance and not running hard to risk race performance. It was an aha and why did I do that moment - I had already run my race during those weeks of training. Now more aware, I will be able to monitor it easily with Tempo’s new Intensity Log.

If you run with an Apple Watch, you should really give Tempo a shot. As a runner, I can tell you with confidence that there is nothing like Tempo out there! Tempo amplifies the power of Apple Watch as a running device.

(I really believe Apple Watch is a superior running Watch, but I will save 'why are you not running with an Apple Watch' part for a different post)

With 2.0 (as mentioned here) Tempo requires annual subscription to access pro features. You can try it for free, but I think you will find it to be an effective training tool to subscribe.

As promised, the original buyers and patrons of Tempo 1.0 will have premium access to all the pro features until August 15th, 2019. Thank you for your support.

Keep Running!

Release Notes for 2.0.1

Tempo has been completely rebuilt, with more insights, graphs, and beautiful new design to keep it simple, yet powerful!

Here’s a quick list of new features:

  • Dashboard: The new dashboard tab shows quick running totals and intensity trend along with fast access to new reports.
  • Cumulative Graph: In addition to the weekly and monthly totals, cumulative graph has been updated to show average pace and highlight days of weeks/months you run.
  • Intensity Log: All new in 2.0 is the Intensity Log. It’s a fantastic addition to understand training pattern and identify stress as well as improvements.
  • Trending Averages: The average runs and miles per week (or month) header on Cumulative Graph screen in 1.0 was so useful that it has been expanded to provide more averages along with a quick current trend for each averaged data point.
  • Notes: We have all been waiting for this one.. With 2.0 you can add your personal insights to every run. It is stored encrypted on your device and backed up to your iCloud account.
  • Tags: This is another frequently asked item that you are going to love. Tags are so useful to remember a run, race, location, etc. Tags on a run also appear on your Runlog screen. You can lookup for all the runs with a given set of tags using the new Filter feature.
  • Pace & Heart Rate Graphs: Yes, it’s here too! Not just static, these graphs are interactive - you can scroll and pinch to zoom.
  • Cadence: This is an experimental feature, but the data looks promising, so it’s been added. More to come.
  • New subscription model: These new pro features require Tempo premium subscription. I hope you will show your support by subscribing. It takes a lot of time and effort to build a quality app like Tempo. I love working on it; but in order for Tempo to survive and thrive as a product for all of us as runners, it requires a lot more than just being a side-project done on nights and weekends.
  • Patronage: If you originally paid for Tempo in the AppStore or paid for pre-2.0 patronage, you will have access to all pro features of Tempo Premium subscription for the next 2 years. Thank you!
  • A lot more behind the scenes: Tempo 2.0 has a lot of behind the scenes optimizations that will further enable next set of features on the roadmap. I look forward to keep working on them and adding more helpful insights to help us run better.

Battery Improvements in Apple Watch Series 2


The latest Apple Watch (Series 2) used only 46% battery for a 3 hours, 35 minutes run vs the first generation Apple Watch that drained most of the battery on a similar run last year. Both the watches are 38mm in size.

Some data from last year:

During a 20 mile run last year (9/19/15), Apple Watch (first generation) drained almost 99% battery.

Apple Watch (2015): Post 20 mile run. Battery at 1%.

Apple Watch (2015): Post 20 mile run. Battery at 1%.

The 20 mile run was in preparation for the Chicago marathon, and based on above data, I knew that Apple Watch won't last for the full marathon at my pace. On race day, I decided to not bring my iPhone so I could carry enough energy gels instead. This meant all of Apple Watch tracking was done using the built-in accelerometer. Surprisingly, I found Apple Watch to be way more reliable than a Garmin Forerunner that went erratic around tall city buildings. Unfortunately, with no paired phone, it also drained 100% battery in the first 16.3 miles.

For my spring 2016 marathon, I discovered power saving mode that disables heart rate sensor during workouts. I verified it during a 20 mile run and used it for the marathon. It worked great, and while the battery lasted for the entire race, I have no heart rate data from that run. It was a hot and humid day to run a marathon and heart rate data would had been an effective way to analyze how I faded off during the last 8 miles.


Same run with the new Apple Watch Series 2:

Last Saturday (9/17/16), I did the same run, a bit longer (21 miles), mostly along the same course, with Apple Watch Series 2. Here are some screenshots taken before, during and after the run,

A quick side experiment:

This was the final long run of my training cycle for Chicago marathon, so I did not want to risk not bringing my phone along and possibly lose or have inaccurate data for it. While I still carried my phone, I decided it was safe enough to do a little experiment at mile 19 and turn off the phone. In the presence of a paired phone, Apple Watch relies on phone GPS reception for better signal and to conserve battery. So I was curious to see how the watch (specifically built-in GPS) would react, when a paired phone disappears in the midst of a run.

The transition was flawless. Apple Watch GPS took over seamlessly when the phone was turned off. This was verified with a course map generated from accurate location data for the whole run.

Not surprisingly, the built-in GPS did use more battery. In the last 20 minutes, battery availability dropped from 57% to 48%. That's 9% for 20 mins with built-in GPS vs 39% for the first 182 mins with a paired phone.

Again, this was mostly to test how well the watchOS and Workout app is built/tested for random GPS source switching. It's impressive that the watch GPS picked up without any glitch and it tracked the remaining run with no issues. In retrospect, considering I didn't want to mess with my data for this run, shutting the phone down was a risky move. I am glad that watchOS and iOS could pick up and sync nicely when the phone was back online.

Results – Battery improvements by numbers:

At mile 19, while still paired with a phone, the new Apple Watch had drained only 39% battery (that's about 41% for 20 miles *). This is substantial improvement over first generation Apple Watch that drained almost 95% battery for the same 20 mile run, done last year.

Mapping the above numbers to total running duration: first generation Apple Watch drained most of the battery for a 3 hours, 35 minutes run, where as the current Series 2 model needed only 46% (**) for the same 3 hours, 35 minutes run. That's over 7 hours of running time on one charge with still some battery power left. (Apple's official tech specs suggest 8 hours of workout from a full battery charge)

Even by including the variance caused due to the above side experiment, 48% for first 21 miles without power saving mode means I can run with the new Apple Watch Series 2 for a full 26.2 miles and still collect all the useful heart rate data.

This is great news for me as a runner and I am sure for many runners out there. If you are looking to buy a new running watch, I would highly recommend Apple Watch Series 2.

Battery was at 96% at start and 57% at mile 19. That's (96-57)/19 = 2.05% per mile.

** Battery drained for 182 minutes was (96-57=39%). That's about 46% for 215 minutes.

Freemium, Patronage & Subscription

With the recent release of version 1.3.1, Tempo is now free to download from the App Store.  

My goal for Tempo is to make it the best training companion app for myself and other runners. That means building it with utmost care and detail, and also maintain our privacy. It requires a lot of time and effort, both in running miles and thorough product development, to test, validate and support such a top quality running app. I love running and working on Tempo, and wish I could do it all the time, but I also have to make sure it is financially sustainable for me. So Tempo will always have a payment model around its usage.

The reality of current App Store economy is that users prefer trying before paying for apps. To allow that, I am making Tempo free to download with all the features enabled. Tempo 2.0 will introduce a subscription model for exclusive access to more advanced features. Subscription will cost at least $3.99 per year to start with.

I am grateful to everyone who bought Tempo on launch. Your feedback, adoption and support has brought us this far. As my thanks to you, when 2.0 arrives, you will have full access to all the advanced features for the first 2 years without requiring any subscription.

Until 2.0 arrives, there is also an option to become an early patron via in-app purchase. This option will also enable full access to advanced features in version 2.0; features that will be otherwise exclusive to subscribed users and original buyers. So if you downloaded Tempo for free, you can still benefit from saving on subscription by becoming an early patron now.

I hope you find Tempo useful in achieving your running goals.

Keep Running!

New Apps We Love

New Apps We Love is the very first section of the Featured tab in the App Store. On Sunday, May 29th, Tempo showed up as the first app listed there.

I ran a marathon on May 28th and was still high from the 26.2 mile run on Sunday evening, when Tempo was featured. Words can not describe the feeling of getting featured in the App Store while already in an elevated state of runner's high. The fact that Tempo is all about running made it even sweeter.

To say that it was really amazing would be an understatement. I was ecstatic! Tempo is a labor of love. Love for the sport of running. Love for building quality software. Software to help me become a better runner. To see that it can be useful for other runners and getting recognized in the App Store is not only gratifying and exhilarating, but also inspiring.

Getting featured has helped Tempo to be noticed by more runners. Runners have been sending e-mails of appreciation - claiming Tempo to be exactly the app they have needed for a while. Some runners have also been gracious to rate Tempo in the App Store. This is very encouraging. It's fuel for me to keep making Tempo better. I am very grateful for all of it.

Thank you, App Store team, for featuring Tempo and allowing it to be discovered by runners all around the world. ❤️

Tempo v1.0

Tempo is now available in the App Store. If you run with your Apple Watch, please do check it out.

You can read Tempo’s story here. To celebrate the launch, here are some more fun facts that I edited out of the original story,

  • I sketched up Tempo’s original screen last year, during a sleepy morning, while staying up with my newborn. It was probably around 5am.
  • That sort of got me into sketching habit during early mornings. Most of them now are before my long runs on the weekends.
  • Many Tempo features have been devised during miles and miles of training on Newton hills and other parts of Boston marathon course along Comm. Ave.
  • During its initial prototyping phase, Tempo was called Runlog.
  • Tempo has been my only running log for my last 2 marathon training cycles.
  • I have been building it for almost a year; crafting it slowly and carefully as my go to running log. As I have said before, I love running and building software, and building Tempo is now my favorite way to do enjoy both!
  • Tempo is the very first project launched under Indie Computing Labs, LLC.

Hello, world!

With self-discipline most anything is possible.

— Theodore Roosevelt

Slowly and steadily, I am almost ready to launch Indie. So I figured I should say hello here.

What does launch mean? It's launching Indie's first project: Tempo. It is code complete, tested and ready to ship. Approved and ready to be released in the App Store.

You can read more about Indie here

Here's why I built Tempo.

Looking forward to this journey!