Concrete Weight Calculator
Concrete weight calculator for a slab, footing, column or countertop. Returns pounds and tons, weight per square foot, and the truck loads or dumpster it takes.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Total weight
- 20,000 lb (10 tons)
- 400 sq ft of slab at 4 in thick, normal weight, reinforced
- Weight per square foot
- 50 lb per sq ft
- IRC Table R301.5 sets a 40 lb per sq ft live load for rooms other than sleeping rooms. Warning: the concrete alone is 50 lb per sq ft, so a framed floor under it needs an engineer
- Concrete volume
- 4.94 cu yd
- 133.3 cu ft of normal weight mix at 150 lb per cu ft
- Loads to haul it
- 14 pickup trips or 1 dump truck load
- A half ton pickup allows about 1,500 lb on its door jamb sticker, and a tandem axle dump truck carries about 10 tons of rubble
- If this is demolition
- 2 heavy debris boxes at 10 cu yd
- Broken up it swells about 50% to 7.4 cu yd, but weight fills the box first: the allowance is 8 to 10 tons
- Planning estimate
- Density varies by mix
- Aggregate, air content and moisture move the density a few percent either way. A structural engineer sizes any framing that carries concrete
Concrete Weight formula
Volume (cu ft) = Length (ft) x Width (ft) x Thickness (in) / 12
Column volume (cu ft) = 3.1416 x (Diameter (in) / 24)² x Height (ft)
Known volume (cu ft) = Cubic yards entered x 27
Weight (lb) = Volume (cu ft) x Density (lb per cu ft), and Tons = Weight (lb) / 2,000
Weight per square foot = Thickness (in) / 12 x Density (lb per cu ft)Worked example
A 9 ft run of poured concrete countertop, 25.5 in deep and 1.5 in thick, normal weight with a wire mesh in it. The volume is 9 x 2.125 x 0.125 = 2.39 cubic feet. At 150 lb per cubic foot that is 359 lb spread over 19.1 square feet, or 18.75 lb per square foot. The cabinets and a plywood substrate carry that, not the floor joists, and the two longest sections still need three people and suction cups to set.
The same house wants an 8 x 8 ft concrete pad 6 in thick for a hot tub, and the only flat spot is a second story deck. That pad is 32 cubic feet and 4,800 lb, which is 2.4 tons and 75 lb per square foot. IRC Table R301.5 asks for 40 lb per square foot of live load, so the pad alone is nearly twice the live load before anyone fills the tub. It is also four pickup trips of material. The deck framing gets designed for it or the pad goes on grade.
Quick reference
| Thickness | Normal weight, lb per sq ft | Lightweight, lb per sq ft | 20 x 20 ft slab, tons |
|---|---|---|---|
| 2 in | 25.0 | 19.2 | 5.0 |
| 3 in | 37.5 | 28.8 | 7.5 |
| 4 in | 50.0 | 38.3 | 10.0 |
| 5 in | 62.5 | 47.9 | 12.5 |
| 6 in | 75.0 | 57.5 | 15.0 |
| 8 in | 100.0 | 76.7 | 20.0 |
| 12 in | 150.0 | 115.0 | 30.0 |
Density is the whole calculation
Concrete weight is volume times density, and density is the only part people get wrong. NRMCA CIP 36 puts normalweight concrete at 140 to 150 pounds per cubic foot. Design practice uses 145 for plain concrete and 150 once reinforcing steel is in the pour, because steel is roughly three times as dense as the concrete it displaces. That 5 pound step is why a cubic yard gets quoted as either 3,915 or 4,050 pounds, and both numbers are right for their case.
Two other mixes move the answer far enough to matter. Structural lightweight concrete uses expanded shale, clay or slate aggregate and runs 90 to 115 pounds per cubic foot. That is about a quarter lighter, which is why it gets specified on frames and parking decks. Heavyweight concrete with barite or magnetite aggregate sits near 230 pounds per cubic foot and turns up in radiation shielding, counterweights and ballast. Fresh concrete also weighs a few pounds per cubic foot more than the cured slab, since it still holds mix water that leaves over the following weeks.
The three limits this number is usually up against
Almost nobody looks up concrete weight out of curiosity. The first limit is the floor. A 4 inch reinforced slab is 50 pounds per square foot. IRC Table R301.5 puts the minimum live load for rooms other than sleeping rooms at 40 pounds per square foot. The dead load allowance sitting under that is nearer 10. A concrete topping poured on wood joists therefore lands about five times the assumed dead load on framing nobody sized for it. A poured countertop is a different case, because the cabinets and the substrate carry it. A hot tub pad, a mud set shower pan or a topping slab on a deck gets an engineer before the truck is booked.
The second limit is the truck. A half ton pickup's door jamb sticker usually allows around 1,500 pounds of payload, which is roughly 30 square feet of a 4 inch slab. 23 CFR 658.17 caps Interstate trucks at 80,000 pounds gross, 20,000 on a single axle and 34,000 on a tandem. A dump truck loaded by volume goes over on the axle long before the bed looks full. The third limit is the container. Broken concrete swells about half again in volume and not at all in weight. A heavy debris box rated for 8 to 10 tons is finished at 4 to 5 cubic yards of solid slab, whatever the box walls suggest.
What this calculator leaves out
The result is the concrete only. It leaves out reinforcing steel weighed separately, forms and shoring, the compacted base under a slab, and any tile, mortar bed or topping over it. It does not price demolition, hauling or disposal. Whether a floor, a deck or a lintel can carry the load is an engineer's calculation, using the full dead plus live combination from the code. Fresh mix still in the drum, water added at the chute and the weight of the mixer itself are outside it. So is the bearing pressure a footing or a pier puts on soil, which depends on the allowable bearing capacity in the soils report.
Code limits that apply
- IRC Table R301.5checked
40 psf live load in rooms other than sleeping rooms, 30 psf in sleeping rooms
If you miss it: A 4 in concrete topping adds 50 psf of dead load, more than the whole live load the joists were sized for
- ACI 318 Sec. 2.3
Normalweight concrete is defined by a density of 135 to 160 lb per cu ft
If you miss it: Assuming a flat 150 for a mix batched with a light local aggregate overstates the dead load on the frame
- NRMCA Concrete in Practice 36
Structural lightweight concrete in-place density of 90 to 115 lb per cu ft
If you miss it: Detailing lightweight and pouring normal weight puts about 30 percent more load on beams than the drawings show
- 23 CFR 658.17
80,000 lb gross, 20,000 lb single axle and 34,000 lb tandem axle on the Interstate
If you miss it: A dump truck loaded by volume goes over on the axle at the scale and the load has to be shed on the shoulder
- IRC R506.1
Concrete floor slabs on grade are at least 3.5 in thick
If you miss it: A thinner pour saves weight and yardage but fails the depth probe at the slab inspection
Rows marked checked produce a warning in the results when an entry crosses the limit. The others are on the plans or on site and this calculator does not test them. Local amendments can be stricter; the adopted edition and the inspector govern.
Mistakes that cost money
- A cubic yard of broken slab is about 4,050 lb, nearly three times the 1,500 lb payload on a half ton pickup's door jamb sticker.
- Ordering a 20 cu yd roll-off for slab debris. It hits its tonnage allowance a third full, and overage costs more than the rental.
- Pouring a topping slab or hot tub pad over wood framing without an engineer; the dead load alone beats the 40 psf live load.
- Figuring lightweight mix at normal weight density. Structural lightweight is 90 to 115 lb per cubic foot, so the load reads about 30 percent high.
- Fresh concrete runs a few pounds per cubic foot heavier than the cured slab, because it still holds mix water that later evaporates.
- Rigging a precast lintel or counter slab without weighing it first. A 10 ft run of 1.5 in counter is close to 400 lb.
Key facts
- Normal weight concrete weighs about 145 lb per cubic foot plain and 150 lb reinforced, so a cubic yard runs 3,915 to 4,050 lb.
- A reinforced concrete slab 4 in thick weighs 50 lb per square foot, so a 20 x 20 ft patio slab is 20,000 lb, or 10 tons.
- NRMCA CIP 36 puts structural lightweight concrete at 90 to 115 lb per cubic foot and normalweight concrete at 140 to 150.
- IRC Table R301.5 sets a minimum live load of 40 psf for rooms other than sleeping rooms and 30 psf for sleeping rooms.
- 23 CFR 658.17 caps Interstate trucks at 80,000 lb gross, 20,000 lb on a single axle and 34,000 lb on a tandem axle.
- A poured concrete countertop 1.5 in thick weighs about 18.75 lb per square foot, so a 40 sq ft kitchen run adds 750 lb.
Frequently asked questions
How much does a yard of concrete weigh?
About 4,050 lb, or just over 2 tons, for reinforced normal weight concrete at 150 lb per cubic foot. Plain concrete at 145 works out to 3,915 lb per yard. Structural lightweight at 90 to 115 lb per cubic foot runs 2,430 to 3,105 lb.
How much does a 20x20 concrete slab weigh?
A 20 x 20 ft slab 4 in thick and reinforced weighs 20,000 lb, which is 10 tons, or 50 lb per square foot. The same slab at 6 in is 30,000 lb, and at 8 in it is 40,000 lb.
Can a wood floor hold a concrete countertop?
A 1.5 in poured counter is about 18.75 lb per square foot and the cabinets carry it, not the joists. A topping slab is the real problem. A 4 in pour is 50 lb per square foot, more than the 40 psf live load IRC Table R301.5 assumes for a room.
How much broken concrete fits in a pickup?
About 1,500 lb in a half ton, taken from the door jamb sticker rather than the badge. That is roughly 30 square feet of a 4 in slab, or a third of a cubic yard. Rubble also rides high, because it swells about 50 percent once it is broken.
Sources and references
- CIP 36: Structural Lightweight Concrete, in-place density of lightweight and normalweight concrete (NRMCA)
- Chapter 3 Building Planning, Table R301.5 minimum uniformly distributed live loads, 2021 IRC (ICC)
- 23 CFR 658.17, Weight: gross, single axle and tandem axle limits on the Interstate System (U.S. Government Publishing Office)
- ASTM C138/C138M, Standard Test Method for Density (Unit Weight) of Concrete (ASTM International)
Next steps for this project
The usual order for a concrete & masonry project. See all concrete & masonry calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.