Snow Weight Calculator
Accurately estimate snow load and total weight for roofs, driveways, and decks.
Calculate Weight of Snow
The length of the roof or ground area.
Please enter a valid positive length.
The width of the roof or ground area.
Please enter a valid positive width.
Average depth of the snow accumulation.
Please enter a valid positive depth.
Fresh, Fluffy Snow (3 lbs/ft³)
Settled Snow (12 lbs/ft³)
Packed/Wet Snow (20 lbs/ft³)
Wind-Packed Snow (35 lbs/ft³)
Solid Ice (57 lbs/ft³)
Select the condition that best matches the snow.
Total Estimated Weight
8,000 lbs
Formula: Volume × Density
Snow Load (Pressure)
20.0 lbs/ft²
Total Volume
400 ft³
Metric Equivalent
3,629 kg
Snow Type Comparison (For Same Depth)
See how weight increases drastically with moisture content.
Detailed Breakdown
| Metric | Value |
|---|
How to Calculate Weight of Snow: A Complete Guide
Winter weather brings beautiful landscapes, but it also brings significant structural challenges. Knowing how to calculate weight of snow is critical for homeowners, facility managers, and construction professionals. Heavy snow accumulation can stress roofs, decks, and driveways, leading to potential structural failures if limits are exceeded.
This guide explores the physics behind snow load, provides the mathematical formulas you need, and offers practical examples to help you assess risk effectively.
What is the Weight of Snow?
The weight of snow is not a constant value; it varies dramatically based on moisture content, temperature, and atmospheric conditions. When we discuss how to calculate weight of snow, we are primarily interested in the "Snow Water Equivalent" (SWE) or the density of the snowpack.
Engineers and architects use this calculation to determine "Snow Load," which is the downward force exerted by accumulated snow on a building's roof. This is typically measured in pounds per square foot (PSF) in the US or kilograms per square meter (kg/m²) internationally.
Who needs this calculation?
- Homeowners: To prevent roof collapse or deck damage during blizzards.
- Contractors: To estimate removal costs based on tonnage.
- Structural Engineers: To design buildings that withstand local weather patterns.
Snow Weight Formula and Mathematical Explanation
To understand how to calculate weight of snow manually, you need to determine the volume of the snow and multiply it by its density. The basic formula is:
Total Weight = Area × Depth × Density
Variables Explained
| Variable | Meaning | Typical Unit | Typical Range |
|---|---|---|---|
| Area | Length × Width of the surface | Square Feet (ft²) | Varies |
| Depth | Height of snow accumulation | Feet (ft) | 0.1 – 5.0+ ft |
| Density | Weight per unit of volume | Lbs per cubic foot (lbs/ft³) | 3 (Fluffy) – 57 (Ice) |
Note: If you measure depth in inches, you must divide by 12 to convert it to feet before multiplying by density in lbs/ft³.
Practical Examples (Real-World Use Cases)
Example 1: The Residential Roof
Imagine you have a flat roof that is 30 feet long and 20 feet wide. A recent storm dropped 18 inches (1.5 feet) of wet, heavy snow.
- Area: 30 ft × 20 ft = 600 ft²
- Depth: 18 inches ÷ 12 = 1.5 ft
- Volume: 600 ft² × 1.5 ft = 900 ft³
- Density: Wet snow is approx. 20 lbs/ft³
- Calculation: 900 ft³ × 20 lbs/ft³ = 18,000 lbs
Result: The roof is supporting 9 tons of snow. The load is 30 PSF (18,000 / 600), which may approach the design limit of older structures.
Example 2: The Driveway Clearance
A contractor needs to clear a driveway that is 50 feet by 10 feet. The snow is light and fluffy, about 12 inches deep.
- Area: 500 ft²
- Depth: 1 ft
- Density: Light snow is approx. 5 lbs/ft³
- Calculation: 500 ft³ × 5 lbs/ft³ = 2,500 lbs
Result: While the volume is high, the weight is manageable for a standard plow truck.
How to Use This Snow Weight Calculator
Our tool simplifies the process of how to calculate weight of snow. Follow these steps:
- Enter Dimensions: Input the length and width of the area in feet.
- Input Depth: Measure the snow depth in inches and enter it.
- Select Snow Type: Choose the description that best matches your snow (e.g., "Fresh, Fluffy" vs. "Packed/Wet"). This automatically applies the correct density.
- Review Results: The calculator instantly updates the Total Weight and Snow Load (PSF).
- Analyze Risk: Compare the "Snow Load" result against your building's structural rating (often 20-40 PSF for residential roofs).
Key Factors That Affect Snow Weight Results
When learning how to calculate weight of snow, consider these six critical factors that influence the final number:
- Moisture Content: This is the biggest variable. "Dry" snow contains very little water, while "wet" snow acts like a sponge. Wet snow can weigh 4-5 times more than dry snow for the same depth.
- Temperature Fluctuations: Freeze-thaw cycles cause snow to melt and refreeze as ice. Ice is significantly denser (57 lbs/ft³) than snow, rapidly increasing the load without increasing depth.
- Time and Settling: Over time, gravity compresses snow. A 2-foot drift might settle to 1 foot, but the total weight remains the same—meaning the density per cubic foot has doubled.
- Rain on Snow: If it rains on top of an existing snowpack, the snow absorbs the rain. This adds massive weight without necessarily adding visible height to the snow pile.
- Wind Drifting: Wind moves snow from one area to another, creating unbalanced loads. A roof might have 6 inches on one side and a 4-foot drift on the other, creating dangerous structural stress points.
- Roof Pitch: While pitch doesn't change the weight of the snow itself, it affects retention. Steep roofs shed snow (reducing load), while flat roofs retain it.
Frequently Asked Questions (FAQ)
1. How much does 1 foot of snow weigh?
It depends on the type. One cubic foot of light snow weighs about 3-5 lbs, while one cubic foot of wet, packed snow can weigh 20 lbs or more.
2. What is a safe snow load for a roof?
In the US, standard residential roofs are often designed for a live load of 20 lbs per square foot (PSF), but this varies by region. Areas with heavy snowfall may require 50+ PSF designs.
3. Does ice weigh more than snow?
Yes. Solid ice weighs approximately 57 lbs per cubic foot, which is nearly three times heavier than wet snow and over ten times heavier than fresh powder.
4. How do I calculate weight of snow on a deck?
Use the same formula: Length × Width × Depth (in feet) × Density. Be cautious with decks, as they often have lower load capacities than main roofs.
5. Why is "Snow Water Equivalent" important?
It tells you how much water is contained in the snowpack. This is crucial for flood forecasting when the snow melts.
6. Can I use this calculator for ground snow load?
Yes. The physics are the same whether the snow is on a roof, a deck, or the ground.
7. How does rain affect the calculation?
Rain adds weight directly. If 1 inch of rain falls on snow, it adds roughly 5.2 lbs per square foot to the existing load.
8. Should I remove snow from my roof?
If the calculated load approaches your roof's design limit, or if you see signs of stress (cracking drywall, jamming doors), removal is recommended. Always prioritize safety.
Related Tools and Internal Resources
- Roof Load Calculator – Estimate the total structural load on your roof.
- Water Weight Calculator – Calculate the weight of water volumes for tanks and pools.
- Winter Home Safety Guide – Essential tips for protecting your home during freezing weather.
- Structural Beam Load Estimator – Advanced tool for construction planning.
- Ice Dam Prevention Strategies – How to stop ice from damaging your roof edges.
- Driveway Clearing Cost Estimator – Calculate fair prices for snow removal services.