Rain to Snow Calculator

Estimate how much snow a given amount of rainfall (liquid equivalent) would produce, using the temperature-based snow-to-liquid ratio meteorologists use for winter forecasting.

Quick Facts

Classic rule of thumb
10:1 ratio (1 in of rain ≈ 10 in of snow)
A rough average; actual snow density varies by storm.
Ratio range
About 10:1 near freezing up to 40:1+ in deep cold
Colder air generally produces lighter, fluffier snow.
Rain/snow cutoff
Precipitation is usually rain at or above ~34°F
Surface temperature alone is only an approximation.

Your Results

Calculated
Estimated Snowfall
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Snow depth equivalent
Snow-to-Liquid Ratio
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Ratio applied to your rainfall
Equivalent in Other Unit
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Cross-check conversion
Snow Type
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Expected density category

Ready

Enter a rainfall amount and temperature, then calculate.

About the Rain to Snow Calculator

This calculator estimates how much snow a given amount of liquid precipitation (rain, or rain-equivalent water content) would produce if it fell as snow instead. It uses the snow-to-liquid ratio (SLR): the depth of fresh snow that one unit depth of melted water produces. The classic shorthand is the "10:1 rule" - one inch of rain-equivalent water makes about ten inches of snow - but meteorologists know the real ratio shifts with air temperature, sometimes running from roughly 10:1 in wet, near-freezing storms up past 40:1 in very cold, dry air.

The formula

Snowfall depth = Rainfall (liquid equivalent) × Snow-to-liquid ratio

In "Auto" mode, this calculator looks up an approximate ratio from the average air temperature you enter, using widely referenced temperature bands: about 10:1 from 30-33°F, 15:1 from 27-29°F, 20:1 from 20-26°F, 25:1 from 15-19°F, 30:1 from 10-14°F, 35:1 from 0-9°F, and 40:1 below 0°F. At or above 34°F, precipitation is treated as too warm to accumulate as snow. In "Fixed" mode it simply applies the traditional 10:1 rule regardless of temperature, which is useful for quick, rough conversions or historical records that only report the 10:1 estimate.

How to get the best results

  • Enter the rainfall as a liquid-equivalent depth - the number you would read off a standard rain gauge, not an existing snow depth
  • Use the average air temperature during the precipitation event, not the daily high or low, for the most representative ratio
  • Compare "Auto" and "Fixed 10:1" results side by side when you want to see how sensitive the estimate is to temperature

Practical context

The snow-to-liquid ratio is genuinely variable in the real atmosphere - it depends on the temperature profile through the whole cloud, crystal habit, wind, and settling/compaction after the snow lands, not just the surface reading used here. Treat this calculator's output as a planning-grade estimate for things like comparing storm scenarios or converting historical rainfall records to a rough snowfall equivalent, not as a substitute for an official forecast or a measured snow depth.

Frequently Asked Questions

What is the snow-to-liquid ratio?
The snow-to-liquid ratio (SLR) is the depth of fresh snow produced by one unit depth of melted (liquid) precipitation. A 10:1 ratio means 1 inch of rain-equivalent water produces 10 inches of snow. The ratio is not fixed - it depends mainly on air temperature, ranging from about 10:1 in wet, near-freezing conditions to 40:1 or higher in very cold, dry air that produces light powder.
Why is the classic 10:1 rule not always accurate?
The 10:1 rule of thumb assumes average winter conditions, but real snow density varies with temperature through the depth of the cloud, not just at the surface. Warmer, wetter snow near 30-33F is denser and closer to 10:1, while colder air well below freezing produces fluffier crystals with much higher ratios, so the same rainfall total can produce very different snow depths.
Can I use this on mobile?
Yes - the calculator is designed to work on any device. For complex multi-input calculations on small screens, landscape orientation gives more room to see all fields and results simultaneously.

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