How it works
Do Stairs Count Differently?
A step counter counts a stair as one step, identically to a step on level ground. Energetically that is badly wrong — climbing a stair costs several times what a flat step costs — and it is the clearest example of the step count measuring the wrong thing.
The physics
Walking on the flat, most of the work is moving your mass forward and swinging your legs; the inverted-pendulum mechanism recycles a substantial share of the energy each stride. Vertical work is close to zero over a level route.
Climbing, you have to lift your entire body mass against gravity, and none of that work is recoverable on the way up. For a 70 kg person on a standard 17.5 cm riser, each stair requires roughly 120 joules of mechanical work, and at typical muscular efficiency around 25 per cent, close to 480 joules of metabolic energy — about 0.11 kilocalories.
A flat step for the same person costs roughly 0.035 to 0.045 kilocalories. So a stair costs something like three times a flat step, and published measurements of stair climbing put the metabolic cost even higher relative to level walking, in the region of 8 to 9 METs against about 3 to 3.5 for ordinary walking.
| Activity | Approx. MET | kcal per step (70 kg) |
|---|---|---|
| Slow walking, level | 2.5–3.0 | ~0.035 |
| Brisk walking, level | 3.5–4.3 | ~0.045 |
| Descending stairs | 3.0–3.5 | ~0.045 |
| Ascending stairs | 8.0–9.0 | ~0.11 |
Descending is closer to flat walking than to climbing, because gravity does the work. What it does instead is load the muscles eccentrically — contracting while lengthening — which produces relatively little metabolic cost but a disproportionate amount of muscle soreness the following day. This is why walking downhill for a long time hurts more afterwards than walking uphill.
What "floors climbed" measures
Devices that report floors use a barometric altimeter — a pressure sensor that detects the small drop in atmospheric pressure as you rise. Most define a floor as roughly three metres of elevation gain, or about ten stairs.
The barometer is a genuinely different sensor from the accelerometer, and it has its own failure modes:
- Weather. A passing pressure front changes ambient pressure enough that some devices register phantom floors while you sit still.
- Lifts and escalators. Many devices detect real elevation gain and credit floors you did not climb. Better algorithms cross-reference the accelerometer to check you were actually stepping.
- Wind and doors. Opening a car door or a gust past a sensor port can produce a brief pressure spike.
- Outdoor hills. Walking up a road climbs real elevation, and most devices count it as floors, which is arguably correct but surprises people.
The Empire State Building comparison
The building's stair climb covers 1,576 steps and about 320 metres of vertical gain. As a step count, that is a modest fraction of a 10,000-step day. As work, it is roughly 170 kilocalories for a 70 kg person — comparable to walking four kilometres on the flat, in about twenty minutes rather than fifty.
Should you count stairs differently?
Your device will not, so the practical answer is to treat floors climbed as a separate metric with its own target rather than trying to convert it into steps.
If you want a rough mental conversion for effort rather than count, three flat steps is a reasonable equivalent for one stair climbed. On that basis a ten-storey climb of about 200 stairs is worth roughly 600 flat steps in energetic terms while registering as 200 on your counter.
The public health case for stairs is unusually strong for something this small. Stair climbing is one of very few genuinely vigorous activities available inside a normal day without changing clothes or allocating time, and studies of stair-climbing interventions have found measurable improvements in cardiorespiratory fitness from short daily bouts over a few weeks.
The general lesson
This is the same limitation that appears in the comparison between walking and running steps, in a sharper form. The step count treats every footfall as equivalent, and footfalls are not equivalent. A step up a stair, a step through sand, a step under a heavy pack and a step across a flat floor differ in cost by a factor of three or more, and the counter cannot tell them apart.
That does not make the number useless. It makes it a measure of movement frequency rather than of work done — which is fine, provided you do not ask it to be the second thing.
Common questions
Do stairs count as steps on a fitness tracker?
Yes, one stair registers as one step. Devices with a barometric altimeter also record it separately as elevation gain or floors climbed.
How many calories does climbing stairs burn?
Roughly 0.11 kcal per stair for a 70 kg person ascending, against about 0.04 for a flat step — close to three times as much.
Why does my tracker show floors when I have not climbed any?
Barometric sensors respond to atmospheric pressure changes. Weather fronts, lifts and even opening a car door can produce readings that look like elevation gain.
Work out your own step count
The step calculator converts the distance between any two places into a step count adjusted for your height, and the route index has twenty worked examples.