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What Is Naismith's Rule?
Naismith's Rule is a classic hiking-time estimation heuristic first proposed by Scottish mountaineer William Naismith in 1892, and remains one of the most widely used baselines for trip planning. This calculator uses the commonly cited metric restatement: 1 hour per 4km of horizontal distance, plus 1 additional hour per 600m of ascent. For example, a route with 8km of distance and 600m of total ascent gives a horizontal time of 8÷4=2 hours, plus an ascent time of 600÷600=1 hour, for a total estimated time of 3 hours.