Hiking Time Estimator
Naismith's rule with Langmuir's descent correction and Tranter's fitness scaling, plus a turnaround time so you finish the walk in daylight.
Will you get back before dark?
The turnaround time is the moment you head back regardless of whether you reached the objective. It is the single most useful number on this page, because the accidents that happen on day hikes overwhelmingly happen to people descending in the dark after pushing on for a summit they were an hour short of.
Where these numbers come from
Naismith's rule, published in 1892, is the base: one hour per 5 kilometres plus one hour per 600 metres of ascent. It has survived for over a century because it is close enough and you can do it in your head.
Langmuir's correction handles the thing Naismith ignored: descent is not free. Gentle downhill between 5 and 12 degrees is genuinely faster — subtract 10 minutes per 300 metres dropped. Steeper than 12 degrees and it reverses, costing 10 minutes per 300 metres, because now you are braking with every step.
Tranter's corrections scale the whole thing by fitness, measured as the time it takes you to climb 300 metres over 800 metres of ground. The multipliers get large quickly, which is the honest part — the difference between a fit walker and someone carrying a heavy pack on their first trip is more than double, not twenty percent.
How to use
- Enter distance, elevation gain and elevation loss for the whole route.
- Pick the fitness level and terrain that honestly describe your day.
- Set a rest allowance — you will stop more than you think.
- Add your start time and sunset to get a hard turnaround time.
Frequently asked questions
What is Naismith's rule?
A walking-time estimate published in 1892 by William Naismith: one hour per 5 kilometres, plus an additional hour per 600 metres of ascent. It has survived because it is simple and roughly right for a fit walker on good ground, which is also the limit of what it claims.
Why does it need corrections?
Because the base rule assumes a fit party on reasonable terrain and ignores descent entirely. Langmuir's correction subtracts time for gentle descent and adds it for steep descent, which is real — steep downhill is slower and harder on the legs than the flat, not faster.
What does the fitness scaling do?
Tranter's correction adjusts the whole estimate by fitness and fatigue, and the effect is large. A less fit party can take half again as long as the base rule suggests, and the correction also accounts for the day getting slower as it goes on rather than proceeding at a constant pace.
Why does the estimate leave out breaks?
Because rests vary enormously and folding them in hides them. Most parties stop far more than they plan to — for photographs, food, navigation, layers and view. Adding an explicit rest allowance makes the assumption visible instead of burying it.
What is a turnaround time and why set one?
The time at which you head back regardless of how close the summit looks. It is set before you start, from sunset and your estimated return time, and it exists because the decision is much harder to make well when you are tired and nearly there. A great many mountain incidents involve continuing past a sensible turnaround.
How much should I trust the estimate?
As a planning figure with generous margin, not a schedule. Ground conditions, weather, navigation difficulty, snow, group size and how the day actually goes all move it. Planning to finish well before dark, rather than exactly at it, is what makes the estimate useful.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.