How snow load calculator works
Snow load is simply weight per area: depth times density. A foot of fluffy powder weighs a few pounds per square foot; the same depth of wet spring snow can weigh five times more. The calculator uses typical field densities — fresh powder about 64 kg/m³ (4 lb/ft³), settled snow 144, wind-packed 240, wet snow 320, and icy layered snow up to 480 kg/m³ (30 lb/ft³).
Enter depth (inches or centimeters), pick the snow type, and optionally add roof area to get the total weight bearing on the structure. Output is the pressure load in psf, kg/m² and kPa, the snow's water equivalent (depth × density ÷ water density), and the category from Light through Extreme.
The result is the load on a flat surface — an upper bound for most roofs, since pitched roofs shed some snow and building codes apply slope, exposure and thermal factors. Use the number to gauge when to clear a roof or whether drifts near a deck are a concern, and compare against your local ground-snow design load rather than treating it as a code calculation.