How Long Does a Hike Take? Naismith's Rule Explained
Naismith's rule estimates hiking time as 1 hour per 5 km plus 1 hour per 600 m of climb. Worked 5, 10 and 15 km examples, and where the rule falls short.
By TrailsPals · Source-based guide. How we prepare our guides · Suggest a correction
Most hikers guess how long a trail will take from the distance alone, and then get caught out by the hills. Naismith's rule is the oldest and simplest fix: add time for climbing. It is an estimate, not a promise, and this post covers how to use it and where it breaks down.
How long does it take to hike 5, 10, or 15 km?
On flat ground at Naismith's pace, 5 km takes about 1 hour, 10 km about 2 hours, and 15 km about 3 hours. Every 600 m of climbing adds roughly another hour. Breaks, photos, and slow terrain are not included, so treat the result as a minimum.
| Distance | Climb | Walking time | Climbing time | Estimate |
|---|---|---|---|---|
| 5 km | 0 m | 1 h | 0 h | 1 h |
| 5 km | 300 m | 1 h | 30 min | 1 h 30 min |
| 10 km | 600 m | 2 h | 1 h | 3 h |
| 15 km | 900 m | 3 h | 1 h 30 min | 4 h 30 min |
What is Naismith's rule?
It is a rule of thumb from the Scottish mountaineer William W. Naismith, who devised it in 1892 while walking Cruach Ardrain. According to Wikipedia's article on the rule, it appears in the last sentence of his trip report in the Scottish Mountaineering Club Journal, and the modern form reads: "Allow one hour for every 3 miles (5 km) forward, plus an additional hour for every 2,000 feet (600 m) of ascent."
The same article lists equivalent forms. One is 5 km/h plus half an hour per 300 m of climb. Another is 12 minutes per kilometre plus 10 minutes per 100 m of climb. They are the same rule written differently, so use whichever is easiest to do in your head.
How do you calculate it?
Two steps, using the numbers from your map or route:
1. Distance in km divided by 5 gives hours of walking.
2. Total ascent in metres divided by 600 gives hours of climbing.
Add them. A 12 km route with 450 m of climb is 2.4 hours plus 0.75 hours, so about 3 hours 10 minutes. Only ascent counts in the basic rule, not descent.
Can you adjust Naismith's rule for fitness and terrain?
Yes, and people have. The Wikipedia article describes several published adjustments:
- Tranter's corrections scale the estimate by fitness. One worked example there: a Naismith estimate of 9 hours becomes 11.5 hours at a fitness level of 25. That section is flagged on Wikipedia as lacking cited sources, so treat the figures as indicative.
- Aitken (1977) keeps 5 km/h on paths, tracks and roads but uses 4 km/h (2½ mi/h) off them, with the same climbing allowance.
- Langmuir (1984) adds descent: on gentle descents (about 5 to 12 degrees) subtract 10 minutes per 300 m, and on steeper ones add 10 minutes per 300 m, since steep downhill slows people down. The article notes that the accuracy of some descent corrections is disputed.
- Group hiking. Langmuir's group formula, as given there, is 4 km/h plus an hour per 450 m of ascent, based on the slowest member.
If you hike with children, a group, or a heavy pack, the group-style numbers are the safer starting point than the original.
Is Naismith's rule accurate?
Only as a starting point. Wikipedia states that the basic rule "assumes hikers of reasonable fitness, on typical terrain, and under normal conditions." It does not include long rests, sightseeing, or navigation trouble, so results are usually treated as a minimum time. It is also not meant for scrambling routes, and the article quotes the view that "No simple formula can encompass the full diversity of mountain conditions and individual abilities."
An alternative is Tobler's hiking function, which gives a walking speed for any slope. On flat ground the same article reports it works out to 5 km/h, matching Naismith's base pace, with speed falling off as slopes get steeper in either direction.
How do you plan a turnaround time with it?
Do the sum, then build in margin on purpose. A few habits that follow from the limits above:
- Add time for every stop you expect to make: lunch, photos, water.
- Use a slower pace if the group is mixed, the pack is heavy, or the trail is rough or wet.
- Pick a turnaround time by the clock, and turn back at that time even if you are short of the summit.
- Compare the estimate with your own record from a similar past hike, since your pace is the number that matters.
That last point is where a recorded track helps. How to record a hiking route covers capturing distance and time, so you can see your real pace per kilometre instead of guessing. The day-hike safety checklist covers leaving an expected return time with someone, and the hiking safety app page explains how TrailsPals handles that return time for a person waiting. Live location sharing depends on signal and battery, so it supplements a plan, not replaces one.
Summary
Naismith's rule: 1 hour per 5 km, plus 1 hour per 600 m of ascent. It is a quick, minimum-time estimate. Adjust it for fitness, group, and terrain, add your breaks, and set a turnaround time before you start.