Concrete Weight Calculator
Estimate concrete slab or block weight from dimensions and selected density.
How the result changes
Only concrete length changes; all other inputs stay at your current values. The line illustrates the formula across the shown range. This is not a forecast of real-world outcomes.
About this calculation
Concrete volume alone does not tell you how much a cured element weighs. This calculator applies a user-selected density to a rectangular slab or block, reporting its geometric volume and estimated mass in pounds and metric tonnes. Estimate concrete weight when planning a concrete pour.
Formula
pounds = length × width × (depth/12) × density in lb/ft³
Worked example
With Concrete length: 12 ft, Concrete width: 10 ft, Concrete depth: 4 in, Concrete density: 150 lb/ft³, concrete volume is 40 ft³.
Inputs and units
Use feet for both plan dimensions and inches for depth. Density is pounds per cubic foot of the concrete mix; an illustrative 150 lb/ft³ may not fit lightweight, heavyweight, or unusually reinforced construction.
- Concrete length (ft): Measure the actual poured slab or block length.
- Concrete width (ft): Measure the poured width without adjoining forms or soil.
- Concrete depth (in): Use the full concrete thickness in inches.
- Concrete density (lb/ft³): Replace the illustrative default with the mix's specified hardened density.
Calculation and worked example
Area is length times width. Dividing inch depth by 12 gives feet, so area times depth yields cubic feet. Multiply that volume by density for pounds; the metric-tonne result converts pounds to kilograms and divides by 1,000 In compact notation, pounds = length × width × (depth/12) × density in lb/ft³.
A 12 ft by 10 ft slab at 4 in thick contains 40 ft³ of concrete. With a 150 lb/ft³ density, the estimate is 6,000 lb, or about 2.722 metric tonnes.
How to use the answer
The mass is a rough material estimate for the specified rectangular element. It should not be used as a lifting plan or structural load calculation without verifying actual mix density, reinforcement, embedded items, and site conditions.
Compare two proposed slab thicknesses to see how mass scales with depth. For a stepped foundation, calculate each rectangular layer separately and add their weights after confirming whether any volumes overlap.
Assumptions and checks
The volume is solid and uniformly dense. The model ignores reinforcing steel, openings, tapered edges, wet-to-dry density changes, and loads added by finishes or equipment.
Do not confuse metric tonnes with US short tons: this page reports the former only for the converted mass. Entering 4 inches as 4 feet would multiply weight by twelve.
At 150 lb/ft³, every cubic foot should weigh 150 lb. Multiply the displayed cubic feet by that entered density independently to verify the pound output.
Common questions
What does the concrete volume result represent?
It is the approximate mass of the measured rectangular concrete volume at your selected pounds-per-cubic-foot density.
What should I check before relying on this result?
Verify concrete thickness and density. For structural or lifting decisions, use project engineering information and actual measured loads.
Inputs
- Concrete length (ft)
- Concrete width (ft)
- Concrete depth (in)
- Concrete density (lb/ft³)