Roof Snow Load Calculator

Calculate the snow load on a roof by entering the dimensions of the roof below and the depth.

How to Calculate Snow Load

Snow load is the additional weight on a roof structure added by snow and ice buildup on the roof. Calculating the snow load is crucial to determining if the structure can handle the additional weight of the snow. The ATC has a snow load hazard tool that can help you identify when a snow load presents a hazard to the structure.

It can be calculated in a few easy steps.

Step One: Find the Volume of the Snow on the Roof

The volume of snow on the roof directly relates to how much it will weigh. To find the volume of snow, start by measuring the footprint of the roof. We strongly recommend against walking on the roof to take these measurements for obvious safety reasons.

Instead, measure the length and width roof from the ground to find the footprint, we’ll account for the pitch later. Keep all measurements in feet to simplify the formulas.

When you have the length and width of the roof as measured from the ground, multiply them together. This will give you the area of the footprint. You can also use our volume calculator.

If you measured from the ground and did not measure the actual dimensions of the roof, then it’s time to account for the roof pitch. If you don’t know your roof pitch, then try our roof pitch calculator to find it.

To account for the pitch, you’ll need to multiply the area by the multiplier for the given roof pitch. You can find a list of multipliers on our roofing calculator. The calculator above applies this formula. If the roof is a flat roof than this step is not needed.

Before moving on, multiply the area by the snow depth in feet to find the volume of snow on the roof.

Step Two: Find the Snow Density

Snow varies in weight depending on the density. Fresh powder weighs much less than wind-packed drifts. Check out our snow weight calculator to find the density of various types of snow.

Step Three: Calculate Snow Load

The final step in calculating the snow load is to multiply the volume of snow on the roof by its density. If you have a density range, then multiply the volume by each part of the range separately to find the minimum and maximum snow load.

You might also be interested in our snow to water volume calculator.