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The best heart rate monitors 2021: the most accurate, responsive monitors

Heart rate monitor
(Image credit: Maridav / Shutterstock)

The best heart rate monitor is a valuable training tool that will help you learn more about your fitness, train more effectively, and track your progress. Virtually all modern fitness trackers and running watches can record heart rate, but not all are accurate. Results between monitors can vary hugely, and poor quality devices can report sudden peaks and troughs when none were expected.

There are two main types of heart rate monitor to consider. Chest strap monitors measure small electrical impulses created as your heart beats. They are more accurate than wrist-worn devices as the signal isn't affected by movement of your arms. They also respond to changes in heart rate much more quickly, which is extremely useful for interval training. However, not everyone finds them comfortable – not least because they need some sweat to establish a good contact with your skin.

The other way of measuring heart rate uses an optical sensor, which shines a light onto your skin and measures changes to the light that's reflected back from your skin. This method is less accurate, but more convenient. It's up to you to decide which you prefer, but here we've tested and ranked the best heart rate monitors to make your life easier.

Garmin HRM-Pro

(Image credit: Garmin)

1. Garmin HRM-Pro

The gold standard for heart rate monitoring

Reasons to buy
+Accurate and responsive+Suitable for all sports+Extra running dynamics
Reasons to avoid
-Relatively expensive

Chest straps are the gold standard, and the Garmin HRM-Pro is our number one choice for the best heart rate monitor. Its reports are accurate and responsive, and in our tests we particularly appreciated its compatibility with a huge range of devices and apps.

This is a true multi-sport device that's suitable for land and water. While many modern sports watches can record heart while swimming, their accuracy varies greatly, and a chest strap is easily the more reliable option. Wireless signals transmit poorly in water, but the HRM-Pro can store up to 18 hours of data before syncing. 

The HRM-Pro also offers running dynamics info, including details of vertical oscillation, stride length and contact time, which are tough or impossible to measure with a device on your wrist.

It's one of the most expensive monitors in this roundup, but not by much, and is a worthwhile investment if you're serious about intensity training.

Read our full Garmin HRM-Pro review

Polar Verity Sense

(Image credit: Polar)

2. Polar Verity Sense

The best option for those who don't like chest straps

Reasons to buy
+Comfortable strap+Reliable data+Switches modes easily
Reasons to avoid
-Fiddly under long sleeves

In the same way that Garmin made its name in GPS technology, Polar has a long heritage in biometrics, and that really shines through in the accuracy of data from the Polar Verity Sense.

It can be worn on your arm or attached to your swimming goggles, making it a good choice for anyone who doesn't get on with a chest strap. It uses an optical sensor like those on a sports watch, but the positioning means there are fewer artefacts from movements like gripping.

The Polar Verity Sense can be a little awkward to wear with long sleeves, but in our tests we were impressed by its ability to transfer data to multiple devices, 20-hour battery life

Read our full Polar Verity Sense review

MyZone MZ-Switch

(Image credit: MyZone)

3. MyZone MZ-Switch

A heart rate monitor that delivers the best of both worlds

Reasons to buy
+Choice of wearing options+Accurate and responsive
Reasons to avoid
-Could use different band sizes-Cluttered companion app

The MyZone MZ-Switch gives you the best of both worlds: an ECG sensor so it can be worn on your chest, and an optical sensor so it can sit on your wrist, arm, or a pair of swimming goggles. It automatically detects where you're wearing it, so there's no need to worry about switching modes, and although it would be nice to have a choice of different arm band sizes, it's comfortable to wear for any type of workout.

That includes swimming; the MZ-Switch is water resistant to 10 meters and stores up to 36 hours of data, so as with the Garmin HRM-Pro, there's no need to worry about syncing when you're in the pool.

When used in chest strap mode, its results compared well with those from the HRM-Pro, though the limitations of technology mean results from the optical sensor have a wider margin of error.

Our main criticism is that the MyZone companion app is too busy and cumbersome for our liking, but the device also pairs with compatible third-party apps so this shoudn't deter you.

Read our full MyZone MZ-Switch review

Polar H9

(Image credit: Polar)

4. Polar H9

Polar's budget chest strap monitor delivers all the essentials

Reasons to buy
+Super affordable+Reliable heart rate data
Reasons to avoid
-Only one Bluetooth connection-Doesn't store workout data

Many of the best heart rate monitors have one major drawback: price. That's where the Polar H9 comes in. This is a chest strap heart rate monitor from the biometrics experts at Polar that's surprisingly affordable, putting it within the reach of runners and cyclists who are keen to get more serious about their training, but can't justify the price of a top-end monitor.

Polar launched the H9 in 2020 as a low-cost alternative to its top-end H10. As a chest-strap monitor from a brand that specializes in biometrics, you can be confident in the accuracy and immediacy of its readings, and it's compatible with a wide array of third-party apps and devices.

What you don't get is the ability to connect to multiple Bluetooth devices simultaneously, or the ability to store data from workouts for syncing later (both of which are offered by the more expensive H10). It ultimately comes down to priorities, but if cash is limited then the Polar H9 is one of the best heart rate monitors you can buy.

Wahoo Tickr

(Image credit: Wahoo)

5. Wahoo Tickr

The best cheap heart rate monitor for cyclists

Reasons to buy
+Excellent app support+Super affordable+Great for cyclists
Reasons to avoid
-Not suitable for swimming

Wahoo is one of the biggest names in cycling tech (particularly for its Kickr line of turbo trainers) so its chest strap heart rate monitor will be a natural top choice if your preferred workout involves two wheels. 

The Wahoo Tickr is compatible with all the most popular fitness apps, including Zwift, Peloton, Runkeeper and MapMyRun, plus Apple Watch and Apple TV, making it a good choice both on and off the bike. It can also generate workout files that sync with Strava, unlike most heart rate monitors.

If you have a little extra cash, the Wahoo Tickr-X adds running dynamics analysis, including cadence, vertical oscillation, and ground contact time (much like the Garmin HRM-Pro). Most of these are metrics that you'd usually need a separate footpod to measure, so they're a welcome addition to minimize the number of running gadgets you're carrying.