# Snow Load Calculator

URL: https://speedycalculator.com/calculators/construction/snow-load/
Last updated: 2026-10-25

> The snow load calculator estimates the weight of snow on a roof from the snow depth and type – fresh, settled, wind-packed, wet or ice – as load per square foot or metre and total weight, and compares it with the roof's design load.

## Inputs

- Snow type
- Snow depth (in, cm, mm, ft, m)
- Roof length (ft, m, in, yd, cm)
- Roof width (horizontal span) (ft, m, in, yd, cm)
- Roof pitch (°, rad)
- Design roof snow load (optional) (psf, kg/m², kPa)

## Results

- Snow load
- Total snow weight on roof
- Share of design load

## Formula

```
Load = snow depth × snow density
Total weight = roof length × width ÷ cos(pitch) × load
Utilisation = load ÷ design snow load
```

## Explanation

Snow density varies enormously: a foot of fresh powder weighs about 5 lb/ft², while a foot of wet, heavy snow or ice can weigh 40–60 lb/ft². Many residential roofs are designed for 20–40 lb/ft² (1–2 kPa) of snow; your local building department publishes the design ground snow load.

### How to use the Snow Load Calculator

- **Snow type**
- **Snow depth**
- **Roof length**
- **Roof width (horizontal span)**
- **Roof pitch**
- **Design roof snow load (optional)**
- Every result field is editable: type into **Snow load** and **Snow depth** plus every other field update to match.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Choose the type of snow, enter its depth, the roof length and width (as measured along the slope) and pitch, and optionally the design roof snow load to see how close you are.

### Tips for an accurate estimate

- Measure the footprint from the ground and apply the pitch multiplier rather than climbing on the roof.
- Add 10% waste for simple gable roofs and 15–20% for hips, valleys and dormers.
- Confirm design snow and wind loads with your local building department before changing framing or roofing.
- Always work with fall protection; roofing is one of the most dangerous trades.

### Common mistakes to avoid

- Using the footprint area instead of the sloped roof area when ordering materials.
- Forgetting starter strips, ridge caps, drip edge and underlayment.
- Mixing up pitch (rise per 12 in of run) with the roof angle in degrees.

### Inputs explained

FieldWhat to enterSnow typeChoose one: Fresh, light snow (≈ 100 kg/m³), Damp new snow (≈ 200 kg/m³), Settled snow (≈ 300 kg/m³), Wind-packed snow (≈ 350 kg/m³) …Snow depthUnits: in, cm, mm, ft, mRoof lengthUnits: ft, m, in, yd, cmRoof width (horizontal span)Units: ft, m, in, yd, cmRoof pitchUnits: °, radDesign roof snow load (optional)Units: psf, kg/m², kPa

### What each result means

- **Snow load** = [Snow depth]×[Snow type]
- **Total snow weight on roof** = [Roof length]×[Roof width (horizontal span)]÷cos(rad([Roof pitch]))×[Snow load]

### Example values

How the main result changes when **Snow depth** changes and everything else stays at the example values above:

Snow depth (in)Snow load (psf)69.36914.051218.731523.411828.092437.46

## Worked example

Inputs — Snow type: Settled snow (≈ 300 kg/m³); Snow depth: 12 in; Roof length: 40 ft; Roof width (horizontal span): 30 ft; Roof pitch: 20 °; Design roof snow load (optional): 30 psf.

Results — **Snow load = 18.73 psf**; Total snow weight on roof = 23,916 lb; Share of design load = 62 %.

## FAQ

**How much does a foot of snow weigh on a roof?**
About 5 lb/ft² for light fresh snow, 18–20 lb/ft² for settled snow and up to 50–60 lb/ft² for wet snow or ice.

**How much snow can my roof hold?**
Typical homes are designed for 20–40 psf; check your local design ground snow load.

**When should I remove snow from a roof?**
When the load approaches the design value, or you see sagging, cracking or sticking doors – use a roof rake from the ground.

**What formula does the Snow Load Calculator use?**
Load = snow depth × snow density.


## Sources

- [ASCE 7 – Minimum design loads, Chapter 7 Snow loads](https://www.asce.org/)