Snow-to-Liquid Ratio Calculator
Estimate snow accumulation from liquid precipitation or snow water equivalent. Adjust the ratio for wet, average, fluffy, or powdery snow so winter forecasts are easier to plan around.
Use QPF, melted snow, or forecast liquid precipitation.
10:1 means 10 inches of snow for 1 inch of liquid.
0.500 in liquid at 10:1 gives a planning range of 4.0 in to 6.0 in.
This is a reasonable planning range when a forecast does not specify snow character, but storms can still vary by layer and location.
Why Snow Ratios Change During a Storm
Temperature Profile
Snow closer to freezing usually compacts into lower ratios, while colder snow can stack up faster for the same liquid amount.
Snow Growth Layer
The amount of ice crystals and supercooled water in the cloud affects whether flakes grow broad and airy or dense and wet.
Wind and Compaction
Wind can break flakes and reduce measured depth. Snow also settles after falling, so storm-total depth can be lower than the fresh accumulation rate.
Local Surface Conditions
Pavement temperature, sun angle, mixed precipitation, and lake or terrain effects can all change what actually accumulates.
Source context: the National Weather Service notes that 10:1 is an old rule of thumb and that ratios can change dramatically within a single snow event.
Common Snow-to-Liquid Ratio Benchmarks
Wet snow
Dense snow near freezing or mixed with rain.
Average snow
Classic 10:1 rule of thumb for quick planning.
Fluffy snow
Colder dendritic snow with more air between flakes.
Powdery snow
Very cold, dry snow that stacks up efficiently.
Snow Ratio Formula
Snow depth equals liquid equivalent multiplied by the snow-to-liquid ratio. In imperial units, 0.50 inches of liquid at a 10:1 ratio produces about 5 inches of snow. In metric units, 10 mm of liquid at a 10:1 ratio produces about 10 cm of snow.
This is a planning estimate, not a replacement for a local winter storm forecast. Use WeatherAI or your local forecast office for changing storm details, precipitation type, and alerts.
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