Steps to calories calculator: calories burned walking

How the calculator works

It uses two published equations, each for the kind of walk it was built for. Both give oxygen use in millilitres per kilogram of body weight per minute, and both are turned into energy at 5 kcal per litre of oxygen, the conversion the Compendium of Physical Activities publishes.

• By steps. A 2021 equation from Moore, Aguiar, Ducharme and Tudor-Locke works from cadence, the steps you take a minute: oxygen use = 1.811 + 0.02014 × cadence + 0.0007427 × cadence². It was built from measurements of 235 adults aged 21 to 84, and it needs no step length, which a step count would otherwise have to guess.
• By distance or time. The ACSM walking equation works from speed in metres a minute and the grade of the slope: oxygen use = 0.1 × speed + 1.8 × speed × grade + 3.5. It is most accurate between about 3 and 6 km/h.

The time of the walk comes from the steps and the cadence, or from the distance and the speed.

From the walk, or in total?

Both figures are shown. Total is everything your body burned during the walk. From the walk takes away 3.5 ml per kg per minute, what a body uses at rest, so it is what the walk added to your day. A fitness watch's "active calories" are the same idea, so set that figure beside them.

A worked example

A 70 kg walker takes 10,000 steps at 100 steps a minute, which takes 100 minutes. The cadence equation gives 1.811 + 2.014 + 7.427 = 11.25 ml per kg per minute. Above rest, that is (11.25 − 3.5) × 70 kg × 100 min ÷ 1000 × 5 = 271 kcal; in total, 394 kcal. The equation's typical error, 2.09 ml per kg per minute, comes to about 73 kcal over this walk, so read the result as a range.

Body weight moves the figure most: the same walk comes to about 213 kcal from the walk at 55 kg and 349 kcal at 90 kg.

Does walking faster burn more per step?

Yes. At 120 steps a minute, the same 10,000 steps take 83 minutes and come to about 333 kcal from the walk, against 271 kcal at 100 steps a minute. A faster step costs more energy, and the walk is over sooner.

What about hills?

A slope adds the ACSM equation's second term. Thirty minutes at 4.8 km/h on flat ground come to about 84 kcal from the walk; on a 5% incline, about 160 kcal, almost twice as much. A treadmill's incline setting is that grade.

Why does my watch say something else?

A watch estimates from your heart rate and its motion sensors, with its own formula, and some show total calories rather than active ones. Neither number is a measurement of your body. If the two disagree by more than the typical error, compare the same kind of figure before deciding which to trust.

Should I eat back the calories I walked?

That is a separate question, with its own trade-offs: Should you eat back your exercise calories? goes through them.

Sources

• Moore CC, Aguiar EJ, Ducharme SW, Tudor-Locke C. Development of a cadence-based metabolic equation for walking. Medicine & Science in Sports & Exercise, 2021, 53(1): 165–173. The simple equation, its sample and its typical error; the paper also gives the ACSM walking equation and the speeds it is most accurate at.
• Compendium of Physical Activities, unit conversions: 1 MET = 3.5 ml per kg per minute, and 5 kcal per litre of oxygen.