Forecasters commonly estimate snowfall from liquid-equivalent rainfall using a rough “10:1 rule” — this calculator applies that ratio, adjustable for different snow conditions.
How it works
Rainfall is multiplied by the snow-to-rain ratio (10:1 by default) to estimate the resulting snow depth.
What this does not include
This is an approximation, not an exact conversion — real snow density varies with temperature, from about 6:1 for wet, heavy snow up to 20:1 or higher for very cold, powdery snow.
How to use this calculator
- Enter the rainfall amount and, if known, a more specific snow-to-rain ratio for the conditions.
Frequently asked questions
Why isn’t the snow-to-rain ratio always exactly 10:1?
Because snow density depends heavily on temperature — colder air tends to produce drier, fluffier snow that piles up more per inch of liquid water.
Is 10:1 accurate for every storm?
No — it’s a widely used average. Very cold storms can produce much fluffier snow (higher ratios), while warmer, wetter storms produce denser snow (lower ratios).
Where does the 10:1 rule come from?
It’s a long-standing meteorological rule of thumb used for quick estimates, not a fixed physical law.
