Cal to kj conversions for exercise

karenosman25

I google searched approx 354 cal's burnt per hr bushwalking/hiking carry up to 9lbs daypack as a general rule for easy calculations I just multiply cals x 4 to get kj's. Does that calorie burn seem right?

L_Master

Kj is the unit of work done. Getting to calories is a little more complex. There are 4.186 kj/Calorie, so to get to Calories you'd actually need to divide by that number.

Which seems depressingly low. However, that assumes we are perfectly efficient, which isn't even close to truth. For cycling for instance, human efficiency tends to vary between 19-26%, which means if you do a 1000kj bike ride, your actual expenditure is closer to 4000kj (most lost to heat, etc.), which when you divide by 4.186 comes out pretty close to a 1:1 relationship.

Whether that works for other activities depends on efficiency. Without knowing that you're basically just guessing in the dark.