How long will my hike take? Naismith’s rule, worked out
This hiking time calculator estimates how long a walk, trek or day hike will take from two numbers you can read off any map or route app: the distance and the total height you climb. It uses Naismith’s rule — the hill-walker’s formula from 1892 — and adds the corrections that make it more realistic: Langmuir’s allowance for descents, Tranter’s adjustment for fitness, your own allowance for a heavy pack or a slow group, and time for stops. You get a total time, the time spent actually walking, and a finish time from your start.
It works in kilometres and metres or in miles and feet. Running pace is a different calculation — use the pace calculator for that — and check daylight with the sunrise and sunset calculator so you are off the hill before dark.
How to use the Hiking Time Calculator (Naismith’s Rule)
- Choose km and metres or miles and feet, and enter the distance, total ascent and total descent from your map or app.
- Pick a descent correction if much of the way down is gentle or steep.
- Keep the standard speeds (5 km/h and 600 m an hour) or change them, and add a Tranter fitness level if you know it.
- Add a percentage for a heavy pack, a group or rough conditions, and your usual stops per hour.
- Enter your start time, read the total and the finish time, and copy the estimate.
Hiking Time Calculator (Naismith’s Rule) features
Naismith’s rule
1 hour per 5 km (3 miles) plus 1 hour per 600 m (2,000 ft) of ascent, with editable speeds.
Langmuir descent corrections
Subtract 10 minutes per 300 m of gentle descent; add 10 minutes per 300 m of steep descent.
Tranter fitness table
Adjusts the time for fitness from 15 (very fit) to 50 minutes (unfit), and warns when a route is too long.
Stops and finish time
Adds rest stops per hour of walking and gives a finish time from your start.
Equivalent flat distance
Scarf’s 7.92 : 1 equivalence shows how far the route “feels” on the flat.
The hiking time formula
William Naismith wrote in 1892 that a walker should allow an hour for every three miles on the map plus an hour for every 2,000 feet of ascent. The metric version is 5 km/h plus one hour per 600 m. For 12 km with 800 m of ascent: 12 ÷ 5 = 2.4 h on the flat, 800 ÷ 600 = 1.33 h of climbing, so 3 h 44 min of walking. With 10 minutes of stops per hour that becomes 4 h 21 min.
Eric Langmuir’s corrections (Mountaincraft and Leadership, 1984) deal with the way down, which Naismith ignored: on gentle slopes of about 5–12° you go faster, so subtract 10 minutes for every 300 m of descent; on steep slopes over 12° you go slower, so add 10 minutes per 300 m. Off-path terrain is commonly planned at about 4 km/h instead of 5.
Tranter’s corrections for fitness
Tranter’s table converts a Naismith time into a time for walkers of different fitness, measured as the minutes taken to climb 300 m (1,000 ft) over 800 m (half a mile). It is a widely reproduced rule of thumb whose original source is not documented, so treat it as approximate. Some values:
| Naismith time | Fitness 15 | Fitness 25 | Fitness 40 |
|---|---|---|---|
| 2 h | 1 h | 1 h 30 | 2 h 45 |
| 4 h | 2 h | 4 h 15 | 5 h 45 |
| 6 h | 3 h 30 | 7 h | 9 h 30 |
| 8 h | 5 h 30 | 10 h | too long |
Hiking Time Calculator (Naismith’s Rule) FAQ
What is the hiking time formula?
Naismith’s rule: one hour for every 5 km (3 miles) plus one hour for every 600 m (2,000 ft) you climb. The hiking time calculator adds descent, fitness, pack and stop corrections on top.
How long does it take to hike 10 km?
About 2 hours on the flat at 5 km/h. Add an hour for every 600 m of climbing — 10 km with 600 m of ascent is about 3 hours of walking, plus stops.
How do I allow for a heavy backpack?
Enter a percentage under Pack, group or conditions. There is no standard figure; 10–20% is a common planning allowance for a multi-day pack. Your own past trips are the best guide.
Is Naismith’s rule accurate?
It is a planning estimate for fit walkers on paths. Fitness, terrain, weather, altitude and group size change real times a lot, which is why the corrections are there and why you should always keep a margin.
Does the calculator work in miles?
Yes. Switch to miles and feet and it uses Naismith’s original 3 mph and 2,000 ft an hour.
What is the equivalent flat distance?
Using Scarf’s 7.92 : 1 equivalence, every metre climbed counts like 7.92 m on the flat; 12 km with 800 m of ascent feels like about 18.3 km of flat walking.