5:1 — Wet, dense snow
A comparatively small snow depth from the same liquid-equivalent amount; a plausible scenario for dense, wet snow.
Rain to Snow Calculator
Estimate snow accumulation from a liquid precipitation forecast using a realistic range of snow-to-liquid ratios. Compare dense, average and fluffy snow, then convert inches, centimeters and millimeters.
Estimate snowfall depth
Instant estimateUse the forecast's liquid-equivalent precipitation, not an existing snowfall depth.
Estimated fresh snowfall
10 in
At 10:1, one inch of liquid is estimated to yield ten inches of snow.
Snowfall = liquid precipitation × snow-to-liquid ratio
Forecast estimate—not a prediction: Snow-to-liquid ratios depend on the temperature profile of the atmosphere, snow crystal structure, wind, compaction, melting and ground conditions. A 10:1 ratio is a convenient example, not a universal rule. Actual snow accumulating on the ground can be significantly different.
The Snowfall Field Manual
How much snow will that rainfall make?
A journey through snow crystals, winter storm forecasts and the surprisingly important relationship between liquid water and fresh snow.
What is a rain-to-snow calculator?
A rain to snow calculator, also called a snowfall calculator or snow-to-liquid ratio calculator, estimates how deep freshly fallen snow might be when you know the forecast's liquid-equivalent precipitation. It multiplies the depth of liquid water by a chosen snow-to-liquid ratio (SLR).
For example, a storm producing 1 inch of liquid-equivalent precipitation might produce around 5 inches of heavy wet snow at 5:1, 10 inches at 10:1 or 20 inches of very fluffy snow at 20:1. All are estimates, not promises.
One inch of water, several winter outcomes
5:1 • Dense5 in
10:1 • Reference10 in
15:1 • Fluffy15 in
20:1 • Powder20 in
The equation
Snowfall calculation formula
Snow depth = Liquid depth × Snow-to-liquid ratio
Both depths must use the same units before multiplication.
Worked example: A forecast contains 12 mm of liquid equivalent. At a snow ratio of 15:1, estimated fresh snowfall is 12 × 15 = 180 mm, or 18 cm (approximately 7.09 inches).
Understanding snow-to-liquid ratios
10:1 — Common reference
A handy starting assumption for calculations, but real ratios are highly variable and may change within one storm.
15:1 — Fluffier snow
An example of relatively low-density snow producing deeper fresh snowfall from the same water amount.
20:1 — Very fluffy snow
Light snow can build considerable depth, but wind and settling can reduce observed accumulation quickly.
Rain-to-snow conversion chart
Estimated fresh snowfall depth for different snowfall ratios. All values below are in inches.
| Liquid equivalent | 5:1 | 10:1 | 15:1 | 20:1 |
|---|---|---|---|---|
| 0.10 in | 0.5 | 1 | 1.5 | 2 |
| 0.25 in | 1.25 | 2.5 | 3.75 | 5 |
| 0.50 in | 2.5 | 5 | 7.5 | 10 |
| 1.00 in | 5 | 10 | 15 | 20 |
| 2.00 in | 10 | 20 | 30 | 40 |
Why snow forecasts vary so much
Atmospheric temperatures
Temperatures throughout the cloud and atmospheric column influence snow crystal formation, melting and density.
Snow crystal structure
Different crystal shapes and aggregates pack differently, creating different snow-to-liquid ratios.
Wind and drifting
Wind redistributes snow and changes the depth you observe at any single spot.
Melting and mixed precipitation
Rain, sleet or melting snow may decrease accumulation compared with a pure-snow calculation.
Settling and compaction
Fresh snow becomes denser over time and can settle during the storm itself.
Ground temperature
Warmer pavement or soil can melt newly fallen snow and prevent depth from building immediately.
Snowfall depth is not the same as snow-water equivalent
Snow-water equivalent (SWE) is the depth of water you would have if the snow melted. Snowfall depth measures the depth of snow itself. This calculator estimates one from the other using an assumed ratio. It is not a measurement of snowpack SWE or a location-specific winter weather forecast.
Rain to Snow Calculator FAQ
How much snow is 1 inch of rain?
At a 10:1 snow-to-liquid ratio, one inch of liquid equivalent produces about 10 inches of fresh snow. At 5:1 it would be about 5 inches, while at 20:1 it could be about 20 inches. Actual ratios vary.
What does a 10:1 snow ratio mean?
A 10:1 ratio means ten units of snow depth for every one unit of liquid water equivalent, measured in the same length units.
How much snow is 1 mm of rain?
At 10:1, 1 mm of liquid equivalent corresponds to 10 mm of snow depth, or 1 cm. At 15:1, it corresponds to 15 mm of snow.
How do you convert inches of rain to snow?
Multiply the liquid-equivalent precipitation in inches by the chosen snow-to-liquid ratio. For instance, 0.5 inch at 12:1 gives 6 inches of estimated snow.
Does 10:1 always work?
No. It is a convenient reference ratio, not a fixed rule. Temperature, cloud microphysics, wind, melting and compaction can cause substantial variation.
What is a snow-to-liquid ratio?
The ratio of freshly fallen snow depth to the depth of water it contains. A 15:1 ratio means 15 inches of fresh snow corresponds to one inch of liquid water.
Can snow have a 20:1 or higher ratio?
Yes, relatively low-density snow can have high snow-to-liquid ratios. However, actual snow ratios depend on storm conditions, and ground accumulation can be reduced by settling and melting.
Does colder weather always mean fluffier snow?
No. Snow density depends on atmospheric conditions throughout the cloud and below it. Surface temperature by itself cannot reliably determine the snow ratio.
Why is the actual snow on the ground less than the estimate?
Possible reasons include melting, compaction, drifting, mixed precipitation and inaccurate or changing precipitation forecasts.
Is this a live snowfall forecast?
No. The calculator uses numbers you provide and does not access real-time weather forecasts. Always follow official local winter weather guidance for forecasts and safety.
Can I convert centimeters and millimeters of snow?
Yes. The calculator accepts liquid-equivalent precipitation in inches, millimeters or centimeters and displays estimated snowfall in inches, centimeters, feet or millimeters.
Is rain-to-snow conversion the same as snowfall prediction?
No. Conversion is a scenario calculation from liquid precipitation and assumed ratio. Forecasting requires much more atmospheric data.
Ready to turn rainfall into a snowfall estimate?
Try a liquid-equivalent precipitation forecast, compare ratios and learn how a storm's snow density changes expected depth.
Methods & further reading: Estimates use snow depth = liquid-equivalent depth × user-selected snow-to-liquid ratio. Reference: National Weather Service for current forecasts and winter weather safety information. This page is an educational calculation tool, not a forecast or travel-safety advisory.