How are the calories worked out?
Walking at a given speed costs a known amount of energy, measured in METs: 1 MET is what you burn sitting still. The Compendium of Physical Activities puts walking at 3.0 METs at 2.5 mph (4 km/h), 3.5 at 3 mph, 4.3 at 3.5 mph and 5.0 at 4 mph. This tool takes the MET for your pace, multiplies it by 3.5 and your weight in kilograms, and divides by 200, for the calories each minute; then counts the minutes your steps take.
Why do heavier people burn more?
Moving more weight the same distance takes more energy. That’s why the same 10,000 steps can be under 300 calories for one person and over 500 for another.
Is this the calories I lose?
It includes what your body would burn anyway in that time, which is about a third of it at an easy pace. The extra calories the walk itself costs are the rest. Either way it’s an estimate, good to 10 or 20%. Walking uphill or on an incline costs much more: the treadmill calories tool counts the slope.
In StepUp
StepUp's Effort metric reads the active energy your iPhone and Apple Watch record, rather than estimating it.
Questions
How many calories do 10,000 steps burn?
Roughly 300 to 500 for most adults: about 380 for someone weighing 70 kg (154 lb) at a moderate pace.
Does walking faster burn more calories?
Yes, a little more for the same distance, because the energy cost per minute rises faster than your speed.
Is an Apple Watch more accurate?
Usually, because it uses your heart rate. StepUp reads the active energy it records rather than estimating.