How it works: This app scores ski runs using real terrain data — slope steepness, vertical drop, and elevation — and compares that to each resort's official difficulty rating.
Use the scoring sliders to match your personal sensitivities: weight Max Slope heavily if short steep pitches are what gets you, or Avg Slope if sustained steepness wears you out more.
Ratings are relative to each resort. A Black Diamond at Camelback (PA) is a very different mountain than a Black Diamond at Jackson Hole (WY). This app preserves that — it scores runs within each resort and assigns computed ratings to match the same Green / Blue / Black / Double Black distribution as the resort's official ratings. So you're always comparing runs within the same mountain, not across resorts.
Verdict column:Overestimated means the resort rates a run harder than the terrain data suggests — it may be more approachable than its badge implies. Underestimated means it's tougher terrain than its rating lets on. Accurate means the computed and official ratings agree.
Trail geometry is from OpenStreetMap. Elevation from SRTM30m via OpenTopoData. Slope angles per NSAA trail rating guidelines.
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Overview
Scoring Weights
Max Slope50%
Avg Slope35%
Elevation10%
Vertical Drop5%
Total: 100%
NSAA rates trails by steepest section (max slope = primary). Avg slope captures sustained difficulty. Elevation proxies exposure and icy conditions. Vertical drop is a minor fatigue proxy.
Adjustments
Classification
Computed tiers use percentile thresholds matched to
the official distribution. Official data from OpenStreetMap.
Filters
Trail ↕
Zone ↕
Official ↕
Drop (ft) ↕
Avg Slope° ↕
Max Slope° ↕
Score ↕
Computed ↕
Verdict ↕
Trail geometry from OpenStreetMap · Elevation from OpenTopoData SRTM30m · Classification per NSAA guidelines