How many calories does climbing burn?

The figures at a glance

Why most figures are too high

The energy cost of climbing has been measured directly since the 1990s, and the results agree with each other. What goes wrong is the sum. A figure such as "700 kcal an hour" takes the rate for climbing and multiplies it by the length of the visit.

Bouldering does not work like that. In a simulated competition round, elite boulderers climbed for about 19 minutes in total, with five minutes of rest between problems.⁴A social session at the gym has more rest than that. Counting the rest as climbing overstates the result by three to five times.

Why your watch struggles with climbing

Watches estimate energy mostly from heart rate and movement. That works for running and cycling, where heart rate rises in step with the oxygen you use. Climbing breaks the link in three ways.

Heart rate runs ahead of the work

Gripping is sustained, static effort, often with your arms above your head. That raises heart rate more than the oxygen use justifies.^{3, 10} One of the first studies of indoor climbing said plainly that the usual heart rate relationship should not be used for this sport.¹

Some of the work uses no oxygen at the time

Short, hard climbing draws on energy systems that do not need oxygen in the moment. In one climbing test with repeated efforts, about 60% of the energy was aerobic and about 40% was not.⁵ That cost is repaid while you rest.

Nobody has tested a watch on a climbing wall

We found no published study that checks any wrist device's energy estimate during climbing. Every accuracy figure comes from walking, running or cycling.^{9, 11} In those tests, no device got closer than 20% on energy.⁹

How Crux works it out

Crux uses what it can measure about your session, in this order.

1. Time on the wall. The Apple Watch times each attempt and each rest. If a session has no timing, Crux assumes a fifth of it was climbing and says so.
2. Height climbed. The watch's altimeter measures each attempt. Every attempt counts, including the ones you fell off.
3. Your body weight, as logged on or before the day of the session.
4. Wall angle, where it is known. Steeper climbing costs more.⁶

With height, Crux uses a model measured on climbers wearing breathing equipment. It has two parts: a cost for every second you hold the wall, and a cost for every metre you climb.⁷

Without height, Crux uses the published intensity for the type of climbing, applied only to the time on the wall.⁸ Rest is counted at a light standing rate. Then Crux subtracts what you would have used anyway, so the result is active energy.

The two methods were built from different data. For the session in the chart they give 285 and 297 kcal, within 4% of each other. That agreement is why we trust them more than a heart rate estimate.

What Crux shows you

• The source. Every figure is labelled: Crux estimate, Apple Watch, Apple Health, or a number you entered.
• Measured or assumed. If the time on the wall was assumed, the figure says so.
• The parts. Tap the figure to see climbing, rest and the extra for hard efforts as separate lines.
• A number you typed always wins.

What we do not claim

• Accuracy for one session. No wearable manages it, and neither do we. The aim is to remove a large, known error, not to be exact.
• That height is the whole story. Traverses and climbing down cost energy and gain no height.
• That you match the average. The studies are small, mostly of experienced men, mostly indoors. Technique changes the cost a great deal.⁷
• That the extra for hard efforts is settled. It is the least certain part, which is why it has its own line.

Checking the model against you

If you log food and weight, Crux can compare its estimates with your real energy balance over several weeks. It needs several weeks of logged food and weight, and at least four climbing days. It will not name a better method when the difference is smaller than the noise.

Common questions

How many calories does an hour of bouldering burn?

It depends on how much of the hour you climb. At a typical 20%, that is 12 minutes on the wall, or roughly 140 kcal of active energy for a 70 kg climber. Heavier climbers and steeper walls use more.

Does sport climbing burn more than bouldering?

Per minute on the wall the cost is similar. Routes keep you on the wall for longer at a time, so a session of routes usually has more climbing in it.

Why is my watch's figure higher than Crux's?

Your heart rate stays raised between attempts and during gripping. A watch counts that as effort. Crux counts time on the wall and metres climbed.

Sources

1. Mermier CM, Robergs RA, McMinn SM, Heyward VH. Energy expenditure and physiological responses during indoor rock climbing. Br J Sports Med 1997;31(3):224–228. Link
2. Watts PB. Physiology of difficult rock climbing. Eur J Appl Physiol 2004;91(4):361–372. Link
3. Giles LV, Rhodes EC, Taunton JE. The physiology of rock climbing. Sports Med 2006;36(6):529–545. Link
4. Cardiorespiratory demands of competitive rock climbing. Appl Physiol Nutr Metab 2021. Link
5. Climbing-specific exercise tests: energy system contributions and relationships with sport performance. Front Physiol 2021;12:787902. Link
6. The estimation of critical angle in climbing as a measure of maximal metabolic steady state. Front Physiol 2021;12:792376.
7. Determinants of climbing energetic costs in humans. J Exp Biol 2021;224(13).
8. 2024 Adult Compendium of Physical Activities, climbing entries. Link
9. Shcherbina A, et al. Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort. J Pers Med 2017;7(2):3. Link
10. The exercise pressor response to indoor rock climbing. J Appl Physiol 2020.
11. Validity of three smartwatches in estimating energy expenditure during outdoor walking and running. Front Physiol 2022;13:995575. Link

Figures in kcal a minute and the worked example are calculated from the published values. Found an error? Email hello@cruxlog.app. This note is general information, not medical or dietary advice.