The Weight of Snow on a Roof calculator estimates the weight of snow on a roof based on the roofs dimensions and the type and depth of snow.
INSTRUCTIONS: Choose units and enter the following:
Weight of Snow (SW): The Weight of Snow on a Roof is returned in pounds, and the volume of melted water is returned in gallons. However, these can be automatically converted compatible units via the pull-down menu.
The dimensions of your roof are used to compute the roof's surface area. That area is based on the ridge length, span and the pitch. The depth of the snow combines with the surface area to compute the volume of snow. With that, and the type of snow, one can reasonably estimate the weight of snow on one's roof.
Ignoring minute traces of other substances, snow is frozen water. This equation uses a median value for the Snow Water Equivalent (SWE) based on the type of snow or ice selected:
To reduce the weight of snow on one's roof, many people use a roof rake to pull large quantities of snow off of the roof.
Type of snow or ice | (kg/m3) |
Fresh New snow | 50-70 |
Damp new snow | 100-200 |
Settled snow | 200-300 |
Depth hoar | 100-300 |
Wind packed snow | 350-400 |
Firn (granular) | 400-830 |
Very wet | 700-800 |
Glacier ice | 830-917 |
Rain/Melt | 997 |