Are Fitness Trackers Accurate?

Through the last few years fitness trackers have grown in popularity. And with the demand for more fitness trackers, the supply has grown as well. Now, there are several brands of fitness trackers and different types. Some fitness trackers are more fashion conscious. Some focus on convenience. Some focus on features. But one thing that all fitness trackers should be is accurate. 

So are they? Are fitness trackers accurate? In most cases, fitness trackers are very accurate, though some have been proven to be more accurate than others. Here’s a little information about how fitness trackers track your fitness and which ones are the best. 

Heart Rate Monitoring

When people consider the accuracy of fitness trackers, they mostly wonder about the accuracy of the heart rate monitor. It is important for people who are training with a focus on cardio or people who have heart conditions to keep an eye on their heart performance. It is also a great indicator of performance progression for both serious and amateur athletes. 

There have been several complaints throughout the years about accuracy issues for various models of fitness trackers, but most companies have stood next to their technology and have been proven accurate. 

One of the more well known complaints were about the Fitbit Charge and Surge. However Consumer Reports tested both of these models at low and high intensities with female and male test subjects and found that the accuracy was always within a 3 beat range, except for one single instance when one of the models recorded 11 beats lower during a high intensity work out. 

How Can You Increase Accuracy?

The best way to increase accuracy in a fitness tracker is to get it in the right position. Many fitness trackers use a specialized technology that uses photoplethysmogram to measure a heart rate. This method uses a light to illuminate the skin and read the light absorption rate through blood flow. It can sound a bit complicated, but knowing how it works helps users understand how to make it more accurate. 

The light needs to have continual contact with the skin to deliver accurate results, so if you have a fitness tracker on your wrist, it might not be as accurate, if you don’t have it fit snugly and positioned a little higher than the bend in the wrist. 

Here are some other options for fitness trackers that aren’t necessarily worn on the wrist. The wrist is the most convenient and probably the most comfortable, but chest straps and armbands may be easier to keep constant contact with the skin.

Chest Straps:

  • Polar H10
  • My Zone MZ-3
  • Garmin HRM Tri
  • Wahoo Tickr X


  • Scosche Rhythm24 HR
  • BodyMedia FIT Advantage Armband Weight Management System


As of right now, the only fitness tracker that has EKG capabilities is the smart watch Apple Watch Series 4. Though it has been found to be accurate in most cases, it’s limited in what it can tell you. Most EKGs have 12 separate leads that are placed in various strategic areas of the body. This will give you the most accurate read of your heart and can detect several conditions. 

The EKG that the Apple Watch has is only one lead, placed on your wrist, of course. This may not be able to detect a heart attack or various other heart related ailments, but it can detect Atrial Fibrillation, a condition that according to the CDC, an estimated that 12.1 million people in the United States will have AFib in 2030

So is it a full on EKG? No. Is it important, and in some cases life saving? Absolutely. 

You should, of course, never replace going to the doctor by wearing the Apple Watch. Instead, use it as a way to validate some of your symptoms to a doctor. The watch should be used as an indicator that something is wrong, not a diagnostic. 

How to Make it More Accurate?

There are a couple things that will make the EKG reading more accurate, and the training module will explain them before you start the test. One of these things is you should be dry and relaxed. You should be able to be motionless for less than a minute. You shouldn’t do an EKG while exercising or right after. This kind of test is called a stress test and should be done in a professional setting. 


GPS is a helpful feature on any fitness tracker, especially if you are using a track my friends sort of an app for race check points or safety reasons. However, even with technology as advanced as it is today, GPS can be finicky, and sometimes it has nothing to do with the device. 


You may find that your tracking device takes shortcuts around bends or will have random spots where you know you didn’t go. This is due mostly to there being a period of time where the GPS couldn’t get a good reading and it is trying to smooth it over by indicating the path that it thinks you may have taken. This of course will lead to some pretty big differences in distances. 


Though its role may seem inconsequential, weather can affect the performance of the GPS in your fitness tracker. Sunny days are more accurate than cloudy days by a small margin, but rainy days can add a 3% error to your workout. 


Any kind of interference can be hard for a GPS to work around. If you run in a wooded area, under bridges, overpasses, or even tall buildings, your GPS could be off by a bit. It’s nearly impossible to run anywhere without at least some interference, but most GPS’s can deal with some of this. 

Overall, GPS is a great feature on a tracking device, but out of all the features available, it may not be the most reliable one out there. Use your GPS, but use it in conjunction with your other features as well. 

Here are some of the best GPS fitness trackers out there: 

  • Garmin Vivoactive 3
  • Apple Watch 4
  • Suunto 9 Baro
  • Coros Apex
  • Garmin Forerunner 935
  • Polar Vantage V
  • Garmin Fenix 5X

Step Counters

As explained in our article about how fitness trackers work, “fitness trackers work by measuring motion. Most employ a 3-axis accelerometer that measures movement in every direction, while some include a gyroscope to measure rotation and orientation. Many include an altimeter to measure altitude.”

So unlike early stages of pedometers that you may have worn on your hip a decade or two ago where you had to enter in your stride in feet and inches, your fitness tracker of today measures your movement based it’s own position. The old pedometers would have a mechanism that clicked and added a step each time it moved up and down. So if you wanted to cheat a little, all you needed to do was shake it. 

If fitness trackers today had that same method of counting steps, they would be wildly inaccurate because most people wear their trackers on their wrist. So if you’re carrying a stack of books, and not waving your arm, you wouldn’t have any steps counted even if you walked several city blocks. Or if you were doing an activity like grating cheese, for example, you would have registered for more steps taken if pedometers measured the same way that they used to. 

Today’s fitness trackers can measure movement in all directions, making any type of activity trackable. You can rest assured that you are getting an accurate reading of every single activity that you do throughout the day. 

Overall, the technology behind fitness trackers is very advanced and impressive. You can keep a fairly accurate eye on everything your body is doing throughout the day, even sleep. Knowing this information will help you have a healthier life by motivating you to push yourself harder each day. In this competitive market, you can be sure that the technology is only going to get more advanced.