Weight of Concrete Slab Calculator
Use this weight of concrete slab calculator to estimate how much a concrete slab weighs based on its length, width, thickness, and concrete density. It is useful for planning, handling, transport, and rough load checks where you need a fast weight estimate in kilograms, tonnes, or pounds. This is a quantity and weight tool, not a structural design calculation.
Typical structural concrete density is ~2400 kg/m³ unless specified otherwise.
How this calculator works
This calculator works out the slab volume by multiplying length, width, and thickness using consistent units. It then multiplies that volume by the concrete density used by the calculator to estimate total weight. The result is shown in kilograms, tonnes, and pounds, with an additional weight-per-area figure.
Formulas used
volume = length × width × thickness
weight (kg) = volume × density (kg/m³)
tonnes = kilograms / 1000
pounds = kilograms × 2.20462
Normal concrete is often estimated at around 2400 kg/m³, but the exact density depends on the mix, reinforcement, moisture condition, and material type. The calculator allows you to choose between 2300, 2400, and 2500 kg/m³, or enter a custom density.
Worked example
Take a slab measuring 4 m by 3 m with a thickness of 100 mm. First convert the thickness to metres (0.1 m) and calculate the slab volume: 4 × 3 × 0.1 = 1.2 m³. The calculator then multiplies that volume by the selected concrete density to estimate the slab weight. Depending on the density chosen, that result is then shown in kilograms, tonnes, and pounds.
Why slab weight matters
Knowing the weight of a concrete slab can help with planning deliveries, lifting, disposal, transport, and rough dead-load checks. It can also be useful when comparing slab thicknesses or understanding how much material is being added to a structure. This tool is for estimation only and does not replace structural design or engineering checks.
Frequently asked questions
Related tools
- Concrete Slab Bag Calculator — how many bags of concrete for a slab
- 2 Inch Concrete Slab Calculator — volume and bag count for fixed 2-inch slabs
- Dry Pour Concrete Calculator — volume, bags and cost for dry-pour slabs
- Concrete Volume Calculator — calculate concrete volume for slabs, footings, and columns
Disclaimer: This calculator is for planning and estimating only. Actual concrete weight varies by mix, density, reinforcement, and moisture content. Use it as a guide, not as a substitute for engineering design.
Related guide
Want to understand this better? Calculate Concrete Slab Weight: A Worked Example with Our Free UK Calculator