Plan your trail time with Naismith’s rule
Before you lace up, a quick time estimate keeps you off the ridge after sunset. The most-used rule in the English-speaking hiking world is Naismith’s rule, published by Scottish mountaineer William W. Naismith in 1892. It is a planning baseline, not a stopwatch — but it is far better than guessing.
The formula
- Base pace
- 1 hour for every 3 miles (≈20 minutes per km) of horizontal distance — about 3 mph.
- Ascent
- Add 1 hour for every 2,000 ft (600 m) of elevation gained.
- Descent (optional)
- Langmuir’s amendment: trim ~10 min per 300 m of gentle descent, or add it on steep, loose ground where knees and footing slow you.
Written as an equation:
Time (hours) = Distance ÷ 3 mph + Ascent ÷ 2,000 ft + Descent adjustment
We add your break minutes on top, because the equation only counts moving time. The result is a realistic door-to-door estimate you can put in your trip plan.
Worked example
A 5-mile (one-way) trail with 1,500 ft of climbing, hiked as an out-and-back at 3 mph, with 30 minutes of breaks and a gentle descent. Distance becomes 10 miles; base time = 10 ÷ 3 = 3.33 h; ascent = 1,500 ÷ 2,000 = 0.75 h; gentle descent trims about −15 min; plus 30 min of breaks. Total ≈ 4 hours 8 minutes of moving + rest time.
When to adjust the baseline
- Heavy pack or rough trail? Drop the base pace to 2.5 mph. A 30-lb pack reliably slows most hikers.
- Fit and light? 3.5 mph is reasonable for a day hike with a waist pack.
- Steep, loose, or exposed terrain? Switch the descent adjustment to "steep" and add a generous rest buffer.
- Kids or a group? Plan to the slowest person’s pace, not the fastest.
Data sources & retrieved: 2026-08-15. Naismith’s rule per W. W. Naismith (1892) and the standard summary on Wikipedia (“Naismith’s rule”); the descent amendment follows Langmuir’s refinements as described by the Ramblers and Ordnance Survey hiking-time guidance. These are planning estimates — always carry a map, light, and extra layers, and turn around with daylight to spare.