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Calcimator

Avalanche Risk Calculator

Estimate avalanche danger rating from slope angle, snowpack stability, recent snowfall, wind loading, and temperature trends. Uses the North American Avalanche Danger Scale.

Inputs

°
in

Results

Danger Rating

3

Travel Advice Code3
Trigger Probability50%
Destructive Size1
How to Use This Calculator
  1. Enter Slope Angle (°) — measure with a clinometer or avalanche probe; 30-45° is the highest risk zone.
  2. Select Snowpack Stability (very stable, stable, moderate, unstable, or very unstable) based on the current local avalanche forecast.
  3. Enter Recent Snowfall (cm in last 48 hours) — new snow loading is a primary avalanche trigger.
  4. Select Wind Loading level (none/light, moderate, or heavy) for the terrain you plan to travel.
  5. Choose Temperature Trend (cooling, stable, or warming) — rapid warming significantly increases wet avalanche risk.
  6. Review Danger Rating, Travel Advice Code, Trigger Probability, and Destructive Size to decide whether to proceed, modify your route, or turn back.

What each input means

Slope Angle
Steepness of the slope in degrees. Most slab avalanches occur on slopes between 30° and 45°.
Snowpack Stability
Assess overall snowpack stability.
Recent Snowfall (48h)
Total new snowfall in the last 48 hours. More than 30 cm significantly increases avalanche risk.
Wind Loading
Wind-transported snow loading on slopes.
Temperature Trend
Recent temperature trend affecting snowpack stability.

What each result means

Danger Rating
North American Avalanche Danger Scale: 1=Low, 2=Moderate, 3=Considerable, 4=High, 5=Extreme.
Travel Advice Code
1=Normal caution, 2=Cautious route finding, 3=Conservative terrain choices, 4=Avoid avalanche terrain, 5=Do not travel.
Trigger Probability
Estimated probability that a human could trigger an avalanche on a susceptible slope.
Destructive Size
Estimated destructive potential on the D-scale: D1 (relatively harmless) to D5 (could destroy a village).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Slope Angle = 35, Snowpack Stability = 3, Recent Snowfall (48h) = 20, Wind Loading = 0 = 5 input(s) provided
  2. Calculate Danger Rating
    3 = 3
  3. Calculate Travel Advice Code
    Travel Advice Code
    3 = 3
  4. Calculate Trigger Probability
    Trigger Probability
    50 = 50

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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