How does an HRM calculate your calories burned?

roguex_1979

I got a new HRM the other day and used it to measure how many calories I burned during two half hour walks. I had put in my weight, heights age and gender and it then took my heart rate from the beginning of the walks to the end and it told me how many calories I had burned.

How does it do that? I obviously know there must be an equation or formula that is factored in using the stats, but how accurate is it really?

I mean, I was reading that the HRM cannot take into account any caffeine that you have consumed during the day, as well as other factors. It seems to take the heart rate and other stats, but what happens if I get a fright? My heart rate goes up a lot for a good few minutes, so does that mean I am burning more calories during those few moments? and how accurate will my calories burned tomorrow be when I start my exercise (cardio) and finish with weights and then switch it off. Surely I will still be burning calories as my heart rate will still be slightly higher.

Can anyone explain to me how it all works?

Thanks!

Mokey41

Nothing is ever totally right. Calories for the food you eat, calories for exercise, it's all an educated guess. It's the reason why I rarely eat back exercise calories, I figure it helps offset some of my other inaccuracies.

ETA: A HRM monitor isn't accurate for weights because the algorithms it uses are based on a significantly elevated heart rate. If your walk wasn't brisk it may be over estimating for that as well. HRM's are really meant for steady start cardio.