Trail Difficulty Calculator
Calculate trail difficulty using the Shenandoah formula: Difficulty = √(2 × elevation gain (ft) × distance (miles)).
Rate any trail Easy to Strenuous.
The Shenandoah National Park trail difficulty formula is the most widely used system for rating trail difficulty in the US:
Formula: Difficulty = √(2 × elevation gain in feet × distance in miles)
Difficulty categories:
- Under 50: Easy (suitable for all fitness levels, children)
- 50–100: Moderate (some fitness required, suitable for most adults)
- 100–150: Moderately Strenuous (good fitness helpful, some scrambling possible)
- 150–200: Strenuous (fit hikers, full-day effort)
- Over 200: Very Strenuous (excellent fitness required)
Example: A 6-mile trail with 1,500 ft elevation gain:
- Difficulty = √(2 × 1,500 × 6) = √18,000 = 134 → Moderately Strenuous
This formula is used by the Appalachian Mountain Club, REI trip guides, and many national park trail systems. It accounts for both the length of a hike and its elevation gain, which together are the primary drivers of physical demand.
Note that trail surface (rocky, rooted, scrambling), altitude, and exposure are not captured in this formula. A technically simple but exposed ridge hike may feel harder than its numerical rating suggests.
Metric conversion: 1 mile = 1.609 km, 1 foot = 0.3048 m. Use the unit selector to enter metric values — the calculator converts automatically.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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