Every hill walker has stood at a trailhead wondering whether there is time to reach the summit and get back before dark. In 1892 the Scottish climber William W. Naismith gave the answer that British walkers have used ever since: one hour for every three miles on the map, plus an hour for every 2,000 feet of ascent. In metric that becomes 5 km per hour plus 1 hour per 600 m of climb. The rule is still taught on Mountain Training UK’s Hill and Moorland Leader and Mountain Leader courses, it underpins route cards in the Duke of Edinburgh’s Award, and US hikers know it in its feet-and-miles form. This guide explains the rule, the later corrections by Langmuir and Tranter, the Alpine-club formula used in German-speaking countries, and works through several examples. To convert the resulting speeds into minutes per mile or per kilometre, use our pace calculator.
The rule in one line
| Unit system | Horizontal | Ascent |
|---|---|---|
| Metric | 1 hour per 5 km (12 min per km) | + 1 hour per 600 m (10 min per 100 m) |
| Imperial | 1 hour per 3 miles (20 min per mile) | + 1 hour per 2,000 ft (30 min per 1,000 ft) |
The answer is moving time for a reasonably fit walker on decent paths with a light pack. It does not include breaks, photo stops, navigation stops or bad weather. The metric and imperial versions are not identical (3 mph is 4.83 km/h, and 2,000 ft is 610 m), but the difference is a few minutes over a day.
Example 1 (metric): a 15 km circuit with 600 m of total ascent.
- Distance: 15 ÷ 5 = 3 h
- Ascent: 600 ÷ 600 = 1 h
- Naismith time: 4 h
Example 2 (imperial): a 12-mile day with 3,000 ft of climbing in the Adirondacks or the Lake District.
- Distance: 12 ÷ 3 = 4 h
- Ascent: 3,000 ÷ 2,000 = 1.5 h
- Naismith time: 5 h 30 min
Total ascent means the sum of every climb on the route, not just the height of the summit above the car park. On a ridge with several tops, add up each rise from your map or GPS app.
Langmuir’s corrections for descent
Naismith said nothing about going down. Eric Langmuir, in Mountaincraft and Leadership (1984, the handbook long used by Mountain Training), added two refinements:
- Gentle descent (5° to 12°): subtract 10 minutes for every 300 m of descent.
- Steep descent (over 12°): add 10 minutes for every 300 m of descent.
Gentle descents are fast walking; steep ones are slow, careful and hard on the knees. For example 1, the 600 m of descent changes the estimate as follows:
| Descent type | Correction | New time |
|---|---|---|
| All gentle (5–12°) | −2 × 10 min = −20 min | 3 h 40 min |
| All steep (over 12°) | +2 × 10 min = +20 min | 4 h 20 min |
| Half and half | −10 + 10 = 0 | 4 h |
Langmuir also suggested that groups should plan around their slowest member, using a more conservative 4 km/h plus 1 hour per 450 m of ascent. For example 1 that gives 15 ÷ 4 = 3.75 h plus 600 ÷ 450 = 1.33 h, about 5 h 05 min, a useful figure for school groups and mixed-ability parties.
Tranter’s corrections for fitness
Philip Tranter’s table converts a Naismith time into a personal one. First measure your fitness: the number of minutes you need to climb 300 m (1,000 ft) over a distance of about 800 m (half a mile) at a steady pace. Then read across:
| Fitness (min) | 2 h | 3 h | 4 h | 5 h | 6 h |
|---|---|---|---|---|---|
| 15 (very fit) | 1 | 1.5 | 2 | 2.75 | 3.5 |
| 20 | 1.25 | 2.25 | 3.25 | 4.5 | 5.5 |
| 25 | 1.5 | 3 | 4.25 | 5.5 | 7 |
| 30 | 2 | 3.5 | 5 | 6.75 | 8.5 |
| 40 | 2.75 | 4.25 | 5.75 | 7.5 | 9.5 |
| 50 (unfit) | 3.25 | 4.75 | 6.5 | 8.5 | too long |
Times are in hours. For the 4-hour route in example 1, a walker with fitness 20 should allow about 3 h 15 min, while one with fitness 30 needs about 5 h. The table also stretches more at longer durations, reflecting fatigue: fitness 25 turns a 9-hour Naismith day into 11.5 hours. Rough ground, heavy packs (around 20 kg), strong headwinds or walking at night are usually handled by dropping one fitness level.
The Alpine-club formula (DIN 33466)
If you hike in the Alps, signposts and guidebooks from the German and Austrian Alpine clubs (DAV and ÖAV) use a different method, standardised as DIN 33466:
- Horizontal: 4 km per hour.
- Uphill: 300 m per hour.
- Downhill: 500 m per hour.
- Calculate the horizontal time and the vertical time (up + down) separately, then add half of the smaller value to the larger one.
For example 1 (15 km, 600 m up, 600 m down):
- Horizontal: 15 ÷ 4 = 3.75 h
- Vertical: 600 ÷ 300 + 600 ÷ 500 = 2 + 1.2 = 3.2 h
- Larger + half of smaller: 3.75 + 1.6 = 5.35 h ≈ 5 h 20 min
That is noticeably more than Naismith’s 4 hours, because the Alpine formula assumes an average hiker with a day pack on mountain paths, not a fit hill walker. Signposted times in Switzerland, Germany and Austria are generally calibrated for that kind of walker too.
Turning the estimate into a plan
- Measure distance and total ascent from a map or app. Add descent if you will use Langmuir or DIN.
- Apply Naismith (or DIN in the Alps).
- Correct for descent, fitness, load and terrain.
- Add breaks. A common planning habit is a short stop every hour or so plus a longer lunch; budget it explicitly.
- Set a turnaround time based on sunset and weather, and stick to it.
For pacing on the day, 5 km/h equals 12 min per km and 3 mph equals 20 min per mile. Our pace calculator converts any planned speed, and the steps to km calculator shows what a hike means for your step count: 15 km at an average step of about 0.75 m is roughly 20,000 steps.
Limits of the rule
- Scrambling, snow, scree and bog are far slower; the rule is meant for walking terrain.
- Heat and altitude reduce speed; above about 3,000 m most people slow down markedly.
- Large groups move at the speed of the slowest person plus regrouping time.
- Trail runners will be much faster; use a pace calculator and their own data instead.
Sources
Naismith’s rule as published in the Scottish Mountaineering Club Journal (1892); Langmuir’s descent and group corrections from Mountaincraft and Leadership (1984 and later editions); Tranter’s fitness table as widely reproduced in mountain-leadership training material; the Alpine-club method from DIN 33466 as used by the DAV. Treat every result as a planning estimate, not a guarantee, and check the weather and daylight before you set off.