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.