The formula
distance = steps × stride · stride ≈ height × 0.415
Where it comes from
A step counter counts steps, not distance: converting them needs your stride length, and that depends mostly on height. The 0.415 factor is the one used for walking at a normal pace; running, the stride is considerably longer and that factor falls short. Calories come from the energy cost of level walking, which runs around 0.53 kilocalories per kilo of body weight per kilometre.
How to work it out by hand
- Measure your stride by walking ten steps and dividing the distance by ten, or estimate it as height × 0.415
- Multiply the steps by the stride to get centimetres
- Divide by 100,000 to convert to kilometres
- Multiply the kilometres by your weight and by 0.53 for the calories
What is worth knowing
Ten thousand steps is not a health recommendation: it came from the brand name of a 1965 Japanese pedometer, the manpo-kei, which literally means "ten-thousand-step meter". Later research finds the big benefit appears well before that, around seven thousand, and flattens out afterwards. The calories here are for the walking alone, not the day: resting expenditure is separate and much larger.