Snow Load Calculator

How it is calculated

The tool treats the snow as a layer of uniform density. load = depth ÷ 100 × density gives the weight per square metre in kg/m², total = load × area gives the weight in kg, and pressure = load × 9.81 ÷ 1000 gives kPa. Inputs are depth in centimetres, density in kg/m³ (fresh powder is far lighter than wet or compacted snow) and roof area in square metres. Depth, density and area must all be above zero or there is no result. The tool uses a single flat figure: it does not apply roof-pitch reduction, drifting, ice or the legal design snow loads of any country, which differ by region and building code.

Common mistakes

• Entering depth in metres or millimetres. The field expects centimetres, so 0.4 instead of 40 gives a hundred times too little.
• Using water density (1000 kg/m³) for snow. Fresh snow is much lighter, and so the load would be overstated.
• Using the same density after rain. Rain-soaked snow can weigh far more than the dry figure.
• Entering the roof's footprint in square feet. The area must be in square metres.
• Treating the result as a design value. It is a rough estimate that ignores slope, drifts and the building code, so use it only to judge when to clear snow.