Fitness watches and trackers' built-in optical heart rate monitors have gotten more and more accurate over the years, but it's an undeniable fact that you need to go straight to the source to get the most accurate results. Some heart rate monitor straps connect directly to popular watch brands like Garmin; other brands like Fitbit don't accept heart rate strap data directly, so you have to use an intermediary app like Myfitnessapp that can send workout and heart rate data to them.
If you can accept some workarounds and don't mind having something strapped to your chest during workouts, the options below will work wonders for the accuracy of your results. These are the best heart rate monitor straps for a variety of fitness watch brands like Garmin, Fitbit, Polar, and others.
Upgrade your fitness data with these optical heart rate monitor straps
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Even if fitness brands sell their own heart rate monitor chest straps, plenty of athletes prefer to make sure the Polar H10 works with it instead due to its acclaimed accuracy. It connects over both Bluetooth and ANT+, so most fitness watches will recognize it. It's comfortable, easy to attach, and comes in multiple colors.
3-year battery life (yes, really!)
Sending data over ANT+ and Bluetooth LE, the Garmin HRM-Dual is its basic strap for tracking heart rate data and variability. With just 1ATM, it's equipped for sweat but isn't designed for swimming; you'll want the HRM-Swim or Pro in that case. But the main benefit of this model is that it's designed to last for 3.5 years with daily one-hour use before you need a new battery.
More than a HRM strap
This versatile model goes well beyond heart rate. If you leave your watch behind, it can measure your steps, calories burned, and intensity minutes. With your watch, it doubles as a running pod, giving you running dynamics data like vertical oscillation, ground contact time, stride length, and vertical ratio. And it has the water resistance necessary for swimming, though the HRM-Swim is more specialized for it.
Slightly more affordable than the H10, the Polar H9 also has ANT+ and Bluetooth LE support but can only connect to one device over Bluetooth at a time instead of two, and it has no onboard memory for working out without a device nearby to store data. If you can do without that — and frankly most people can if they work out with a watch — then it'll save you money compared to the H10 with the same overall quality.
Dual Bluetooth and ANT+
You don't need a strap that matches up exactly to your favorite smartwatch brand! The Wahoo Tickr will connect to its own app to send heart rate and caloric data, to ANT+ devices like Garmin watches, or to compatible third-party apps like Strava, which can then send data to your app of choice like Fitbit.
Use your arm instead
While you could only call this Polar heart rate armband a "strap" very loosely, it does strap onto your arm so we're going to include it here for some variety, in case a chest strap isn't the best fit for you. Like the H10, it has internal memory for independent workouts, or Bluetooth LE/ ANT+ to connect to your watch of choice.
Strap in for serious fitness
When it comes to the best fitness watches, most of them will either accept Bluetooth or ANT+ connections to your heart rate chest strap or armband of choice, so you can choose your favorite regardless of the watch brand you prefer. At that point, smarter watches will recognize the strap's data and disable its own heart rate sensor, and then the watch will deliver that data to your phone once you complete the workout.
Of course, if you want the best synchronicity between your watch and strap, you can choose a strap that matches your current watch. For example, Polar Pacer Pro owners can choose the H10, or Garmin Forerunner 255 users can choose the Garmin HRM-Dual. You know they'll work well, and they should transfer over to whatever watch you use next regardless of the brand.
Fitbit owners have things a bit harder, because none of its watches actually work with any chest straps. But its users have found a workaround: take a strap like the Polar H10 with internal memory and complete an independent workout that transmits to the Polar Flow app. Then set up the Polar app to export to an intermediary app like Myfitnessapp, which can in turn be set up to export workout data to Fitbit.
It's not convenient, because it means you can't actually use your Fitbit tracker during the workout for data. But at least you'll get that ultra-accurate heart rate data, and then you can wear your Fitbit outside of workouts for standard health data.
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Michael is Android Central's resident expert on fitness tech and wearables, with an enthusiast's love of VR tech on the side. After years freelancing for Techradar, Wareable, Windows Central, Digital Trends, and other sites on a variety of tech topics, AC has given him the chance to really dive into the topics he's passionate about. He's also a semi-reformed Apple-to-Android user who loves D&D, Star Wars, and Lord of the Rings.
For wearables, Michael has tested dozens of smartwatches from Garmin, Fitbit, Samsung, Apple, COROS, Polar, Amazfit, and other brands, and will always focus on recommending the best product over the best brand. He's also completed marathons like NYC, SF, Marine Corps, Big Sur, and California International — though he's still trying to break that 4-hour barrier.