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:
- (L) Ridge Length
- (S) Span of Roof
- (P) Pitch of Roof
- (D) Depth of Snow on Roof
- (sT) Type of Snow
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 Math / Science
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 |
Hydrology (Water, Rain and Snow) Calculators:
- Snow Pack to Liquid Water Calculator
- Volume of water in snow or rain
- Weight/Mass of Snow on an Area.
- Weight of Snow on a Rectangular Area.
- Weight of Snow on a Roof.
- Weight of Snow on a Polygon Shaped Area.
- Volume of Water in a Rainfall
- Flow Rate of Broad Crested Weir
- Water Capillary Rise.
- Volume of Flood Water.
- Number of sandbags needed to build a wall or dike.
- Water Saturation Ratio
- Rain Fall Harvesting Calculator
- Peak Discharge from Drainage Basin Runoff
- Gauckler-Manning Equation
- Cipolletti Weir Flow Rate
Gable Roof Calculators
- Gable Roof Area: This computes the surface area of a gable roof based on dimensions and pitch.
- Trusses Needed for Roof: This computes the number trusses need for a roof including gabled roof.
- 4x8 Sheathing for Gable Roof: This computes the total surface area of a roof, the number of 4x8s and framing nails needed for a gabled roof based on the length, span, pitch and overhang.
- Gable Roof Sheathing Cost: This computes the number of 4x8 sheets (32 ft² each) needed to cover a gabled roof based on the ridge length, roof span, overhang and the pitch and applies the unit cost of a 4x8.
- Nails for Gable Roof Sheathing: This computes the approximate number of nails needed to nail 4x8 sheets to trusses or rafters on a roof based on the dimensions of the roof, spacing of nails on the edges and field of the 4x8, and whether blocking or clips are use.
- Purlins for Gable Roof: This computes the total number and length of purlins for a simple gable roof based on the ridge length of the roof, the roof pitch and the span of the roof.
- Metal for Gable Roof: This estimates the metal panels and trim needed for a metal roof for a simple gabled roof based on the roof dimensions.
- Metal Screws for Gable Roof: This computes the number of special screws needed for a metal roof.
- Shingles for Gable Roof: This computes the number of shingles (bundles), underlayment, ridge shingles, starter strip, and roofing nails for a gable roof.
- Gable Roof Shingle Cost: This estimates to shingle a basic gable roof based on dimensions (length, span, pitch and overhang) and the unit price of a bundle of shingles.
- Underlayment for Gable Roof: This estimates the cost of underlayment to cover a basic gable roof based on the area of a roof computed from the dimensions (length, span, pitch and overhang) and the unit price underlayment material.
- Roofing Nails for Gable Roof: This estimates the number of roofing nails needed for a common gabled roof based on roof dimensions and wind conditions.
- Rafters for Gable Roof: This computes the total number of rafter boards (roof joists) for a gabled roof based on the ridge length, pitch and span. It also returns the length of the ridge board, and the length and number of rafter ties and collar ties.
- Rafter Length: This computes the length of the rafters based on the span, pitch and overhang.
- Gable Roof Geometries: This computes the length of rafters, pitch and cut angles, soffit and facia base widths of a gable roof.
- Weight of Snow on Roof: This computes the weight of snow on a gable roof based on roof dimensions, depth and type of snow.