What formula is used for BMI?

gbarn

When I use the "standard" Mass/Height2" it doesn't match the result shown in cronometer. For a height 6'3" and weight 196 lbs your calc shows 24.4 BMI. My spreadsheet calc using the formulas below shows 24.5 BMI. Not a huge difference but I just wonder why. I tried both formulas converting my US inches and lbs to metric but they only differed by .01 (24.50 for US and 24.49 for Metric).

BMI = mass (kg) / height2 (m) (that is height squared)
or
BMI = 703 × mass (lbs)/height2 (in)

source: https://www.calculator.net/bmi-calculator.html?

Hilary

Hi @gbarn ,
We use the formula BMI = mass (kg) / height squared (m) to calculate BMI. In your profile, you will see 2 values. One is BMI and the other is Body fat %. these are different values. BMI is a chosen value used as a health indicator, whereas body fat percent calculates body composition regardless of height or weight.
If the BMI value reported is indeed conflicting with calculated values, please contact support@cronometer.com with screenshots of your account details.

gbarn

As I was creating the support email I found out why... conometer's calc rounds the conversion between US height and weight to metric before the BMI calculation. The online calculators and spreadsheets I used do this conversion after the BMI calculation using the un-rounded height and weight calculations. I humbly suggest that using the un-rounded height and weight numbers in the BMI calculation would be more accurate. In my case the differ 24.5 vs. 24.4. Probably not a big deal in the grand scheme of things but not as accurate as it could be in my opinion.

Hilary

Thanks for the suggestion George,
We will have a look at how we round our values in our BMI calculation.
Thanks for the time and effort you put into looking into this. We really appreciate it! Rest assured, BMI is not used to calculate any values within Cronometer, so will not affect any other values found within the app. For tracking purposes, however, we do hope we can offer the most accurate values possible, so will certainly look into it.
Best,
Hilary