What this calculator does
Naismith's rule, published in 1892, estimates walking time as the distance at a chosen flat pace plus an hour for every 600 metres of ascent. Twelve kilometres at 5 km/h with 500 m of climbing comes to 3 hours 14 minutes: 2 hours 24 for the distance and 50 minutes for the ascent.
Splitting the two contributions is what makes the rule useful rather than just a number. On a flat route the ascent term vanishes and the estimate is simply distance over pace. On a steep one the climbing can account for more time than the distance does, which is why two routes of the same length can differ by hours.
The formula
The distance contribution is the distance divided by the flat walking pace. The ascent contribution adds one hour for every 600 metres climbed, which is the original Naismith allowance. The two are added. Descent is not deducted or added, which is the rule most obvious simplification.
| Term | Meaning |
|---|---|
| Naismith rule | Distance at flat pace plus one hour per 600 m of ascent. |
| Flat pace | Walking speed on level ground, conventionally 5 km/h for a fit walker with a light pack. |
| Total ascent | Cumulative height gained, which includes every climb on an undulating route rather than just the net gain. |
| Tranter corrections | A later adjustment table for fitness and fatigue, which Naismith alone does not account for. |
The inputs explained
| Field | What to enter |
|---|---|
| Distance (km) | Route distance in kilometres. |
| Total ascent (m) | Total ascent in metres. On an undulating route this is the sum of every climb, not the difference between start and finish heights. |
| Flat-ground pace (km/h) | Flat walking pace in km/h. 5 is the Naismith original; 4 is more realistic with a heavy pack or in a group. |
When to use it
Planning a day walk
Working out whether a route fits the available daylight is the ordinary use, and the ascent term is what separates a realistic estimate from an optimistic one.
Comparing two routes
Two routes of the same distance can differ by hours if one climbs considerably more, which the split contributions show directly.
Filing a route plan
An expected finishing time left with someone is standard mountain practice, and it needs to be based on something more considered than distance alone.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much time does ascent add?
The same 12 km route with increasing amounts of total ascent.
| Total ascent | Estimated hiking time | Distance contribution | Ascent contribution |
|---|---|---|---|
| 0 m | 2 h 24 min | 2 h 24 min | 0 h 0 min |
| 300 m | 2 h 54 min | 2 h 24 min | 0 h 30 min |
| 500 m | 3 h 14 min | 2 h 24 min | 0 h 50 min |
| 1000 m | 4 h 4 min | 2 h 24 min | 1 h 40 min |
Questions
How accurate is Naismith rule?
Reasonable for a fit walker on good paths, and optimistic for most other cases. It takes no account of terrain underfoot, pack weight, group size, weather or fatigue over a long day. Most walkers find it needs padding, particularly in the afternoon of a long route.
Does it account for descent?
No, and that is its best-known limitation. Gentle descent is faster than flat walking while steep descent is slower, and Naismith treats all of it as flat. Later refinements such as Tranter corrections and Langmuir adjustments attempt to handle this.
What pace should I enter?
5 km/h is the Naismith original and suits a fit walker with a light pack on good ground. Drop to 4 for a heavy pack, rough terrain or a group, since a group moves at the pace of its slowest member plus the time lost regrouping.
Should I add time for breaks?
Yes, the rule covers moving time only. Lunch, photographs, navigation stops and regrouping easily add an hour to a full day, and they are not optional in practice. Adding 25% to the calculated figure is a common working allowance.
For running pace over a measured distance, see the pace calculator. For predicting race times across distances, see the race time predictor.