Fitbit Charge 2 vs. Polar FT4: How accurate are calories burned?

[Silkelyss]

Hello everyone! I'm kind of new to Fitbit (have had it since two weeks ago) and I read a lot of post about how inaccurate the calories burned on a Fitbit can be, so I decided to take it to the test. I compared my calories burned on my Fitbit Charge 2, compared them with my Polar FT4 (which has a chest strap, which is more accurate) and here are some results!

User information

Fitbit Charge 2

Weight: 60.9 kg (my actual weight this morning)

Height: 163 cm

Age: 21

Polar FT4

Weight: 60 kg (it has no option for decimals, so I go for the lower number usually. So if I weigh between 60 kg and 61 kg, I choose 60)

Height: 163 cm

Age: 21

Workouts

1) Elliptical (20 minutes)

• Fitbit [ cal burned: 162 cal | AVG ♥: 138 | MAX ♥: 147 ]
• Polar [ cal burned: 139 cal | AVG ♥: 141 | MAX ♥: 151 ]

2) Milon circle (36 minutes)

• Fitbit [ cal burned: 294 cal | AVG ♥: 146 | MAX ♥: 175 ]
• Polar [ cal burned: 270 cal | AVG ♥: 147 | MAX ♥: 176 ]

3) Walking (15 minutes, 10% incline, 5 km/h)

• Fitbit [ cal burned: 131 cal | AVG ♥: 149 | MAX ♥: 159 ]
• Polar [ cal burned: 118 cal | AVG ♥: 151 | MAX ♥: 161 ]

Overall

• Fitbit: 587 calories burned
• Polar: 527 calories burned

Fitbit says I burned 60 calories more. The heartrate usually only has a difference of about 2-4 bpm.

So all in all, I’m very pleased to see that the difference is quite small, and maybe can be even explained because of the almost 1 kg difference in the user settings? I’m not sure how much of a difference this actually makes!

(I do however still question Fitbit's calories burned from steps, seems quite high…)

Hope this was an interesting read 🙂

[JohnnyRow]

Interesting comparison. Thanks.

Fitbit compared very well to chest strap for heart rate.

Not surprised at a bit more variation in calories burned as those cannot be measured directly and different companies probably use different algorithms.

[Daves_Not_Here]

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@Silkelyss wrote:

Hope this was an interesting read 🙂

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@Silkelyss - thanks, and very interesting!

My opinion is that some people get hung up on the supposed inaccuracy of tools, to which I say, welcome to the real world concept of observational error.  My experience over the last 2 months has been that, after tracking eating and activity in Fitbit, I lose about 1 pound per 3,500 calorie deficit.  Therefore, I don't really care that individual measurements are high or low as long as the overall trend is accurate, which in my case, it is.

[WavyDavey]

It's nice to see the Max HR between the two is so similar. So I'd expect the calories burned to be close.

[FortyAPM]

Heart rate measurements between the two would be similar as they are using similar technologies.  I highly recommend using a chest strap because the variance between the light and electrode technologies differ very greatly.  I found that my HR was nearly 50bpm lower on my optical fitbit vs a chest strap from polar when performing sprints (HIIT).