Snow Load Calculator
Estimate snow load in pounds per square foot from snow depth and a selected or manual snow density.
in
Settled / Packed (~15 lb/ft³)
Result
Estimated Snow Load
15.0 psf
How to Use the Snow Load Calculator
Enter the snow depth on a roof or surface and choose a snow type to estimate the load in pounds per square foot (psf). Different snow types vary enormously in density — freshly fallen powder is much lighter per inch than settled, wet, or icy snow — so the same depth of different snow types can put very different loads on a structure.
Load (psf) = (Depth in Feet) × Density (lb/ft³)
Example
12 inches (1 foot) of settled/packed snow at roughly 15 lb/ft³ produces a load of 1 × 15 = 15 pounds per square foot. The same 12 inches of ice at roughly 57 lb/ft³ would instead produce 1 × 57 = 57 pounds per square foot — nearly four times as much load for the same depth.
Common Use Cases
- Getting a rough sense of roof snow load after a heavy snowfall.
- Comparing how much heavier a load becomes as fresh snow settles or turns to ice.
- General awareness before deciding whether to clear snow off a roof or structure.
FAQs
- Is this accurate enough for structural decisions? No — this is a simplified estimate for general awareness only, not a substitute for a structural engineer's calculation. Real roof snow load design uses ground snow load maps, exposure and thermal factors, roof slope, and local building code requirements well beyond a simple depth-times-density estimate.
- Why does snow density vary so much? Freshly fallen, fluffy powder traps a lot of air and is very light per unit volume. As snow sits, it settles and compacts under its own weight, and can also partially melt and refreeze, both of which dramatically increase its density and the load it puts on a surface.
- What should I do if I'm worried about roof snow load? Contact a structural engineer or your local building department, especially after unusually heavy or wet snowfall, rather than relying on a rough estimate like this one for safety-critical decisions.