Roof Snow Load Calculator

About this calculator

Snow load on a roof is calculated from three inputs: the roof area, the snow depth, and the snow’s density (fresh powder is much lighter than wet, compacted, or ice-crusted snow) — total load = area × depth × density, usually expressed as pounds per square foot (psf) or kilograms per square meter to compare directly against a roof’s design load rating. The tricky part is density: fresh powder can be as light as 5-7% the density of water, while wet or settled snow can approach 20-30%, meaning the same visual depth of snow can represent a wildly different actual weight.

Building codes like ASCE 7 in the US specify minimum design ground snow loads by region, which architects and structural engineers use to size roof framing during construction, but homeowners reach for this calculation reactively — after a heavy or unusually wet snowfall, to judge whether the accumulated weight is approaching a level worth clearing before it stresses the structure. Older roofs, flat or low-slope roofs, and roofs that have already collected several storms without melting are the cases where this check matters most.

Enter your roof area, snow depth and snow type (which sets the density), and this calculator estimates the total and per-square-meter snow load on your roof.