Snow Load Estimator
Put a number on the snow sitting on your roof. Enter the roof footprint, the snow depth, and what kind of snow it is, and see the total weight in kilograms and tonnes.
Your results
Worked example
A roof with a 10 m by 8 m footprint carries 30 cm of settled snow:
- Snow volume: 80 m² × 0.30 m = 24 m³
- Total weight: 24 m³ × 200 kg per m³ = 4,800 kg, or 4.80 tonnes
- Per square metre: 0.30 m × 200 kg per m³ = 60 kg per m²
That is roughly the weight of three mid-size cars spread over the roof. The same 30 cm as fresh snow would weigh 2,400 kg; as wet snow, 9,600 kg. Snow type moves the answer far more than a few centimetres of depth.
How this calculator works
The density values are estimates drawn from common snow science ranges: fresh snow near 100 kg per m³, snow that has settled and compacted for days near 200, and wet spring snow near 400. Ice layers from freeze and thaw cycles weigh more than any of these. Drifting also matters: wind piles snow unevenly, and a drift at a roof valley or against a higher wall can carry several times the average load shown here.
Common questions
When should I clear snow off my roof?
Warning signs matter more than any single number: doors sticking, new ceiling cracks, sagging, or creaking sounds call for prompt clearing and professional advice. Flat and low-slope roofs, and older roofs, deserve attention sooner than steep modern ones.
Is it safe to go up and shovel it myself?
Roof work in winter is a leading cause of serious falls. A roof rake from the ground handles most houses. If the load has to come off and you cannot reach it from the ground, hire a crew with proper fall protection.
Safety disclaimer: the figures on this page are an estimate only, not a structural assessment. Snow density values are stated estimates, and real loads vary with drifting, ice layers, and roof shape. If you are concerned about your roof, consult a structural engineer or your municipality. Mississippi Maple accepts no liability for decisions made using this calculator.