Naismith's Rule Calculator
Scotland-specific walking time estimator. Enter distance and ascent, pick your fitness, terrain, weather and pack weight — get a realistic time for your hill day in seconds.
How it works
Naismith's Rule was published in 1892 by William W. Naismith, a Scottish mountaineer and one of the founders of the Scottish Mountaineering Club. It's the foundational walking-time formula for UK hillwalking and has barely changed since.
The base formula is straightforward: allow 1 hour per 5km of distance, plus 1 hour per 600m of ascent. A 10km walk with 400m of ascent comes out at 2 hours 40 minutes by Naismith's original reckoning. In practice this is only a starting point — it assumes a fit walker on good ground in good weather with a light pack.
Tranter's corrections (1972) extended Naismith to account for fitness level and carry weight. We simplify Tranter's full lookup table into five fitness tiers, because form-based lookups are tedious and the simplification sits well within the ±25% real-world variance.
Scottish-specific adjustments come on top: peat bog and scree/boulder fields get their own terrain multipliers (most generic calculators ignore these), strong wind and whiteout get weather multipliers, and pack weight is tiered for day / multi-day / expedition kit. The result is a more realistic time estimate for Scottish hill conditions than you'd get from a generic Naismith tool.
Related walking guides
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Five Munros within 90 minutes. Use the calculator with each one's distance and ascent figures.
The Cobbler Route Guide
11km, 880m of ascent, mountain-path terrain. Try those numbers in the calculator above.
West Highland Way Planning
Multi-day kit adds ~15% to your time. Use the calculator per stage for a realistic schedule.