Researchers in Aberystwyth University have found that popular brands of fitness trackers can overestimate the number of calories burned while walking by more than 50 per cent.

Dr Rhys Thatcher has said that devices had an “inherent tendency” to overmeasure.

The tests, which were carried out for the BBC X-Ray programme, measured the amount of oxygen a volunteer used during ten minutes of walking and running sessions on a treadmill before comparing it to a range of various fitness trackers.

The fitness trackers on offer were varied in price, ranging from £20 ($AUD 36) to £80 ($AUD 147).


The Fitbit Charge 2 was very accurate in testing calories while the volunteer was running, underestimating by 4 per cent. However, when the volunteer was walking, the tracker overestimated by 50 per cent.

Dr Thatcher explained:

“If you want to know the exact number of calories that you are burning during an exercise session then it doesn't matter which device you use, you have to interpret the data with some caution”

Fitbit have said that they’re confident about the performance of their product. 

Have you noticed that your fitness tracker over estimates the number of calories burned?

This article originally appeared on Over60.