Best Heart Rate Monitors (2025), WIRED Tested and Reviewed

We tested and recommend all of the heart rate monitors below, which do a pretty impeccable job. But what does this data mean?

Heart rate zones: If someone tells you they’ve been doing 80/20 training, they’ve been doing heart rate zone-based workouts. Heart rate zones are an easy way to break down your range of effort during exercise. Zones go from 1 to 5, with 5 indicating working at 90 to 100 percent of your maximum heart rate. Zone 2 represents training at 60 to 70 percent of maximum heart rate and represents light training. 80/20 training is intended to build endurance and means that 80 percent of your runs should be in Zone 2. If your heart rate monitor doesn’t tell you your zone, you can calculate it using Polar’s simple tool.

Maximum heart rate: Some monitors can inform you of your maximum heart rate, which is the number of beats your heart can reach during exercise. This is useful for knowing when you’re training at peak intensity and can be used to create heart rate zones. Factors like your age and fitness level can influence what that maximum heart rate will be. You can generate an estimate of your maximum heart rate by simply subtracting your age from 220 and use that at a starting point.

VO₂ max: The term VO₂ max stands for maximum rate of oxygen your body can consume during exercise; the higher the better. It provides a useful indicator of your ability to sustain intense effort for long periods. Calculating this accurately is done in lab conditions, so heart rate monitors and watches often use their own algorithms to approximate that lab testing.

Heart rate variability: Heart rate variability measures the intervals between heart beats and is measured in milliseconds. High HRV readings are considered better than lower ones, because it means that the body is responding in a resilient way to stress. However, your HRV readings can differ widely from one person to another because they can be influenced by age, fitness level, or even when the measurement was taken.

Resting heart rate: This is the number of times your heart beats in one minute when at rest, which is a simple indicator of your current level of cardiovascular fitness and general well-being. Typically, your heart rate is supposed to sit anywhere from 60 to 100 bpm at rest. A low resting heart rate is associated with athletes, because the heart has been trained to be more efficient. But an uncharacteristically low or high RHR could mean that something is not quite right.

Calories burned: A heart rate monitor looks at your effort based on your heart rate and uses the company’s own algorithms to offer an indicator of how many calories you’ve burned during a workout. Heart rate is one of the strongest, if not the strongest indicators of effort, which means a heart rate monitor is one of the most accurate ways to get this information.