The short answer: a half marathon walk (21.1 km, 13.1 miles) is roughly 26,000 to 33,500 steps depending on your height, about 29,000 for someone near 173 cm (5'8"). At 3 mph it takes a little over four hours, and a 70 kg person uses roughly 1,070 calories in total, about 760 of them above what they'd burn sitting.
Steps by height
The table uses the pedometer convention of step length being about 0.414 times height, which is an estimate; real ratios ranged from roughly 0.41 to 0.47 in a 2025 study of 313 adults, and your step usually lengthens when you speed up. See steps in a mile and steps in a 5K for the same method on shorter distances.
| Height | Steps in a half marathon (estimate) |
|---|---|
| 5'0" (152 cm) | about 33,500 |
| 5'4" (163 cm) | about 31,300 |
| 5'8" (173 cm) | about 29,500 |
| 6'0" (183 cm) | about 27,800 |
| 6'4" (193 cm) | about 26,400 |
How long does it take?
This is simply distance divided by speed. For other speeds and conversions, use the walking pace chart. The earlier page's times at 4, 5, 6.5 and 7.5 km/h are the same arithmetic. Event time limits vary, and the earlier page's remark that organised events usually allow 5 to 6 hours is something we couldn't source, so check the limit and pacing rules for your event.
| Walking speed | Time for 21.1 km (13.1 miles) |
|---|---|
| 2.5 mph (4.0 km/h) | 5 h 15 min |
| 3.0 mph (4.8 km/h) | 4 h 22 min |
| 3.5 mph (5.6 km/h) | 3 h 45 min |
| 4.0 mph (6.4 km/h) | 3 h 17 min |
Calories
Using the Compendium of Physical Activities rating for walking at 3 mph (3.5 METs) and the formula calories equal METs times body weight in kilograms times hours, the totals are below, with the extra above resting in brackets. The earlier page's figures, such as 840 for 70 kg, were lower than this method gives and disagreed with our calorie page, so we've rebuilt them. They're estimates and individual results vary.
| Body weight | Calories for 21.1 km at 3 mph (extra above resting) |
|---|---|
| 55 kg (121 lb) | 840 (600) |
| 70 kg (154 lb) | 1,070 (760) |
| 85 kg (187 lb) | 1,300 (930) |
| 100 kg (220 lb) | 1,530 (1,090) |
Drinking during a long walk
The earlier page advised drinking regularly and "staying ahead of thirst rather than catching up to it." Current guidance says almost the opposite. The 2015 international consensus statement on exercise-associated hyponatremia (Hew-Butler and colleagues, Clinical Journal of Sport Medicine) recommends drinking according to thirst, and identifies overdrinking as a cause of dangerously low blood sodium, which is a particular concern for people who exercise at a slower pace and drink a lot. Event-specific risk factors include long duration (over about four hours) and easy access to fluids, which describes a half marathon walk. Drinking to thirst, the statement says, should protect against both excessive dehydration and overdrinking. We haven't reviewed the evidence on snacks or electrolyte drinks, so we've dropped that advice; eating what you normally tolerate on long walks is a reasonable practical approach, but it's our suggestion, not a researched protocol.
Building up
The earlier page set out an 8 to 10 week plan from 5 to 8 km walks up to a 16 to 18 km longest walk and a taper. That is a suggestion, not a tested program. A trial in novice runners found that a graded program based on the "10% rule" didn't reduce injuries compared with a standard program (Buist and colleagues, 2008), so there's no strong evidence for a specific progression, though gradual build-up is the common approach, and our beginner's guide is a starting point. Break in your shoes well before the event; walking shoes covers what is known about fit. If you haven't exercised for a while or you have a health condition, check with your doctor before taking on a distance like this.
Sources
- Pedometer step-length convention (0.413 x height for women, 0.415 x height for men), as described by step-length calculators; includes a 2025 Sensors study of 313 adults with step-length-to-height ratios of about 0.41 to 0.47. getfitcraft.com
- Ainsworth BE, Haskell WL, Herrmann SD, et al. 2011 Compendium of Physical Activities: a second update of codes and MET values. Medicine & Science in Sports & Exercise. 2011;43(8):1575-1581. pacompendium.com
- Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clinical Journal of Sport Medicine. 2015;25(4):303-320. ovid.com (commentary on the statement)
- Buist I, Bredeweg SW, van Mechelen W, Lemmink KA, Pepping GJ, Diercks RL. No effect of a graded training program on the number of running-related injuries in novice runners. American Journal of Sports Medicine. 2008. PubMed
Correction note: an earlier version of this page advised staying ahead of thirst when drinking during the walk and suggested electrolyte drinks, gave calorie figures (such as 840 for 70 kg) lower than the standard method gives, said events typically allow 5 to 6 hours, and presented a 10-week training plan as if established. The drinking advice contradicts the 2015 international consensus, so it was replaced; the calories were rebuilt; the event time limit and the electrolyte advice were removed; and the plan is labelled as a suggestion. The consensus statement is cited from a commentary and news summaries, not the full text. The step-length convention is taken from calculator pages. This article is for informational purposes and does not replace medical advice. This is general information, not medical advice.