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Allow 1 hour per 5 km (3 miles) of horizontal distance plus 1 hour per 600m (2000 ft) of ascent. Descent is not subtracted in the basic rule.
Time = (Distance km / 5) + (Ascent m / 600) hoursApply multipliers for trail conditions: good trail 1.0×, rough trail 1.25×, off-trail/boulder 1.5–2.0×, snow/scree 1.5–2.5×.
Adjusted time = Naismith time × Terrain factorHeavy packs (over 15 kg) add 10–20%. Beginner hikers add 20–30%. Fit experienced hikers on familiar terrain may use 0.8× on flat sections.
Final time = Adjusted time × Fitness factor + Rest breaksUpdated: July 2026
Naismith: (10/5) + (800/600) = 2 + 1.33 = 3.33 hours (~3h 20m). Add 15 min breaks → plan 3.5–4 hours total.
Imperial Naismith: (14/3) + (4000/2000) = 4.67 + 2 = 6.67 hours. Rough trail ×1.25 = 8.3 hours. Start early, carry headlamp.
8 km, 900m gain, off-trail factor 1.75: base 2.5 hr × 1.75 = 4.4 hours. Add weather and navigation buffer — plan 5–6 hours.
Apply elevation gain on the climbing segment only. A 1000m up / 1000m down hike adds 1000m to Naismith, not 2000m — unless descent is on difficult terrain requiring extra time.
Add 30–60 minutes buffer before sunset or weather cutoff. Naismith averages fail on tired legs, navigation errors, and group delays — common on return legs.
Accurate hike time estimates prevent getting caught after dark and help plan water and food. Naismith's rule provides a baseline from distance and elevation gain, adjusted for terrain, pack weight, and group fitness. This calculator estimates moving time plus rest breaks.