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Snow Load Calculator
Estimate the weight of snow on a roof.
Snow load
—
Per square foot.
| On a 100 ft² roof | — |
|---|---|
| Depth | — |
| Type | — |
| — |
Show our math
Enter your figures above to see the step-by-step working.
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How the Snow Load Calculator Works
Snow load is the weight of snow pressing down on a roof, measured in pounds per square foot (psf). It depends on depth and how dense the snow is: fresh powder weighs about 0.5 psf per inch, while wet or packed snow can be 1.25–1.5 psf per inch. A foot of packed snow is about 15 psf — 1,500 pounds spread over a 100-square-foot section of roof.
Most residential roofs are designed for 20–40 psf, but ice dams and drifting can concentrate far more. If you’re near the limit, clear the roof or consult a professional.
snow load = depth (in) × density (psf per inch)
Frequently Asked Questions
How much does snow weigh on a roof?
It depends on density: about 0.5 psf per inch for fresh snow, up to 1.5 for wet or packed. A foot of packed snow is roughly 15 psf.
How much snow load can a roof handle?
Many homes are rated for 20–40 psf, but check local building code and watch for drifting and ice.
When should I clear my roof?
If the load nears the design limit, or ice dams and heavy wet snow build up — clear it or hire a pro.
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