Every Heartbeat Matters: A New Heart Rate Algorithm for Suunto Run
You are eight kilometers into a tempo run, holding what feels like the right effort, and you glance at your wrist to check that you are where you want to be. It tells you whether to hold the pace, ease back, or press a little harder. When you train by heart rate zones, every reading feeds a decision.
Runners have told us how closely they watch that number, and how much it matters that it reflects what their body is actually doing. We have been listening.
On August 20, 2026, Suunto Run receives a firmware update with an all-new wrist heart rate algorithm, developed by Suunto, built to make your running heart rate more accurate and more worth acting on.
What Is New in This Update
- A new firmware version for Suunto Run, releasing August 20, 2026.
- An all-new wrist-based heart rate algorithm, developed in house by Suunto.
- Focused specifically on heart rate accuracy while running.
- The interface and the way you use your watch stay exactly as they are.
- Free, and delivered straight to the watch you already own.
This is an improvement to how your watch reads and interprets your pulse, not a redesign of how you use it. There is one thing to do: install the update.
What This Means on Your Next Run
Wrist heart rate works by reading blood flow through the skin, and running is a demanding environment for that measurement. Arm swing, changes in pace, cold weather and the sharp climb in effort at the start of a session all make the signal harder to read cleanly. The new algorithm is designed to handle those moments better.
In practice, that means:
- Fewer readings that clearly do not match the effort you are putting in.
- A more dependable view of how your body responds through a session.
- More confidence when you use heart rate zones to steer intensity.
- A more reliable data foundation for managing your training load over time.
For runners who work to zones, that last point matters most. A zone-based session only works if the number driving it holds up, and this update is about strengthening that foundation.
What the Data Shows
Suunto ran internal comparative testing across a range of running scenarios, measuring Suunto Run against a reference heart rate device. Data points that deviated by more than 5 bpm from the reference device were reduced by approximately 45 percent compared with the previous algorithm.
In plain language: across the test data, the readings that stood noticeably apart from the reference device became considerably less common. The improvement shows up in the outliers, in the moments where the number on your wrist looked out of step with the run you were having.
Full figures and testing detail are in the Testing Notes at the end of this article.
Based on Suunto internal testing against a reference heart-rate device. Results may vary depending on the user, activity and wearing conditions.
How to Get the Update
Installing takes a few minutes:
- Update the Suunto app on your phone to the latest version.
- Make sure your watch has enough battery to complete the installation.
- Connect Suunto Run to the Suunto app and check for a software update in the app or on the watch.
- Follow the on-screen prompts to complete the installation.
The update will be rolled out gradually. Availability timing may vary by market and user.
Getting the Best from Wrist Heart Rate
A few habits help your watch read you well, whichever algorithm is running:
- Keep the watch in steady contact with your skin, with the strap snug enough to stay in place while you run.
- Remember that wearing position, skin condition, ambient temperature and the type of movement can all influence a wrist-based reading.
- For sessions where you want the most detailed heart rate data, pair Suunto Run with a compatible heart rate belt.
Wrist heart rate is a training tool, and a good one. It is not a medical device, and it is not designed to replace one.
Every Reading, Taken Seriously
You care about every heartbeat. We take every reading seriously. Update your Suunto Run and get more accurate, more dependable heart rate data on your next run.
Testing Notes
Suunto conducted internal comparative testing of the new and previous wrist heart rate algorithms across multiple running scenarios, using a reference heart rate device as the comparison benchmark.
- Data points with an error greater than 5 bpm: 7.394 percent with the previous algorithm, 4.036 percent with the new algorithm, a relative reduction of approximately 45 percent.
- Accuracy within ±5 bpm: improved from 92.606 percent to 95.964 percent.
- Accuracy within ±10 bpm: improved from 96.468 percent to 97.803 percent.
These results come from Suunto internal testing and are not an independent third-party certification. A reference heart rate device serves as a comparison benchmark rather than an absolute measure of heart rate. Results may vary depending on the user, activity and wearing conditions.
