Concrete Weight Calculator
Find the total weight of a concrete pour, from its volume and density.
Reviewed by the ToolNestr Editorial Team — July 2026
How the concrete weight calculator works
Concrete weight follows directly from its volume and density. Normal-weight concrete — the standard mix used in slabs, footings, and columns — weighs about 150 pounds per cubic foot, or roughly 4,050 pounds per cubic yard. Lightweight concrete, made with a lighter aggregate like expanded shale instead of gravel, is noticeably lighter at around 100 to 115 pounds per cubic foot, often chosen for elevated slabs where reducing structural dead load matters.
To find the weight of a slab, first find its volume in cubic feet — length times width times thickness, all in feet — then multiply by the density. Because slab thickness is usually given in inches, it needs converting to feet (divide by 12) before multiplying. The calculator also reports the weight per square foot, a handy number for checking against a floor system's load rating.
This weight is for the plain concrete only; it does not include rebar, which typically adds a modest 1 to 3% on top for a standard reinforced slab. Knowing total weight matters for sizing formwork and shoring, checking that an elevated wood or steel floor structure can carry a new slab poured on top of it, and confirming that lifting or transport equipment for precast concrete elements is rated for the load. For any load-bearing or elevated application, verify against your structural design and a qualified engineer.
Enter dimensions
Length, width in feet, thickness in inches.
Pick the concrete type
Normal-weight or lightweight mix.
Read the weight
Total pounds, tons, and weight per square foot.
The formula explained
Volume
= L × W × (thickness⁄12). A 10×10 ft slab, 4 in thick: 10×10×0.333 = 33.3 ft³.
Weight
= volume × density = 33.3 × 150 = 5,000 lb.
Per square foot
= weight ÷ area = 5,000 ÷ 100 = 50 lb/ft².
Worked example
A 20×15 ft driveway slab, 6 inches thick, normal-weight concrete.
Where concrete weight matters
Elevated slab loading
Pouring a new topping slab on an existing wood or steel-framed floor requires checking that structure's load rating against the added weight before pouring.
Precast lifting and transport
Precast panels, planters, and blocks need a crane, forklift, or trailer rated for their actual weight before they're moved or set.
Formwork and shoring design
Wet concrete's full weight bears on the formwork and shoring until it cures, so temporary supports must be sized to the pour's actual weight, not just its footprint.
Shipping and delivery estimates
Estimating the weight of precast or tilt-up panels before delivery confirms the truck and route can legally and safely carry the load.
Real-world context
Adding a topping slab over an existing wood-framed deck shows why this calculator matters before, not after, a pour: an 8×6 ft slab at 6 inches thick weighs 24 ft³ × 150 lb/ft³ = 3,600 pounds — a load that must be checked against the deck framing's rated capacity before pouring, since most residential deck framing isn't designed for that much added dead load.
A precast lightweight concrete panel for easier handling shows the density choice in action: a 4×8 ft panel, 5 inches thick, in lightweight concrete at 110 lb/ft³ weighs about 1,467 pounds — noticeably lighter than the same panel in normal-weight concrete would be, which is exactly why lightweight mixes get specified for precast elements that need to be lifted by hand or a smaller crane.
A long garden walkway shows a simple planning use: a 40 ft by 3 ft path at 4 inches thick weighs 6,000 pounds, about 3 tons — useful context for anyone wondering whether a small skid-steer or wheelbarrow-based delivery plan can realistically move that much material across a yard without vehicle access.
In all three cases, the weight-per-square-foot figure is often the more useful number for a quick structural sanity check, since most floor and roof framing tables express their load capacity in pounds per square foot rather than a total slab weight — comparing the two directly avoids a unit-conversion mistake at exactly the moment it matters most.
Common misconceptions
"Lightweight concrete is weaker, so it's only for non-structural use." Not necessarily. Structural lightweight concrete is engineered and code-recognized for real structural applications — bridge decks and high-rise floors commonly use it specifically to reduce dead load while still meeting strength requirements, not because it's a lesser substitute for normal-weight concrete.
"The weight of a slab is basically the same as any other building material at that thickness." Concrete is unusually dense. At roughly 150 lb per cubic foot, a 4-inch concrete slab weighs about 50 pounds per square foot — several times heavier than a comparable thickness of wood-frame construction, which is exactly why elevated concrete pours need a structural check that a wood deck surface wouldn't.
Related calculators
Frequently asked questions
How much does concrete weigh?
Standard normal-weight concrete weighs about 150 pounds per cubic foot (roughly 4,050 pounds per cubic yard). Lightweight concrete, made with a lighter aggregate, runs closer to 100 to 115 pounds per cubic foot.
How do I calculate the weight of a slab?
Find the slab volume in cubic feet (length × width × thickness in feet), then multiply by the concrete density. A 10×10 ft slab, 4 inches thick, at 150 lb/ft³: 10 × 10 × 0.333 × 150 ≈ 5,000 pounds.
Why does concrete weight matter?
It sets the load on the formwork, the subgrade or supporting structure below the pour, and what a crane, truck, or lift needs to be rated for when moving precast pieces. Elevated slabs on a wood or steel-framed floor must also be checked against the structure's load capacity.
Does the weight include rebar?
No — this calculates the weight of the concrete itself. Rebar adds a relatively small amount of additional weight (a typical reinforced slab might add 1-3% of the concrete weight in steel), so for precise structural load calculations, add the rebar weight separately.
Sources & references
This tool uses standard formulas and reference values from:
- • American Concrete Institute — ACI 318, Building Code Requirements for Structural Concrete. concrete.org
- • ICC — International Residential Code (IRC), span, footing and framing tables. codes.iccsafe.org
- • APA – The Engineered Wood Association, allowable span and load guidance.
Estimates for planning only. Span, load and code values vary by jurisdiction — verify against your local adopted code and a licensed engineer before building.