How much does concrete weigh?
Normal-weight concrete weighs about 150 lb per cubic foot (2,400 kg/m³) — or roughly 4,050 lb per cubic yard (about 2 short tons). A standard 4-inch residential slab adds 50 lb for every square foot of floor area (about 240 kg/m²).
Skip the arithmetic: use the concrete weight calculator → Enter your slab dimensions and concrete type and it returns the weight in pounds, kilograms and tonnes instantly.
1. The short answer — concrete density by type
Concrete is dense because it is mostly stone. Sand, gravel and water pack together tightly, and when the cement paste cures and binds them, the result is a solid mineral mass. The exact density depends on the aggregate (stone) used, the water-cement ratio and any additives, but for design and estimating purposes three standard values cover the vast majority of real pours:
| Type | lb/ft³ | kg/m³ | Typical use |
|---|---|---|---|
| Normal weight | 150 | 2,400 | Slabs, footings, foundations, driveways |
| Lightweight | 110 | 1,760 | Structural decks, precast blocks, topping slabs |
| Heavyweight | 200 | 3,200 | Radiation shielding, counterweights |
Density values: ASTM C138 / ACI 318 industry constants. Normal-weight concrete varies from roughly 140–160 lb/ft³ in practice; 150 lb/ft³ is the standard design value.
2. Weight by slab thickness — per square foot and per square metre
For a flat slab the weight per unit of floor area depends only on thickness. Multiply thickness (in feet) by 150 lb/ft³ to get the load in lb/ft²; multiply thickness (in metres) by 2,400 kg/m³ to get kg/m². Here are the most common thicknesses:
| Thickness | lb/ft² | kg/m² |
|---|---|---|
| 3 in (75 mm) | 37.5 | 180 |
| 4 in (100 mm) | 50 | 240 |
| 5 in (125 mm) | 62.5 | 300 |
| 6 in (150 mm) | 75 | 360 |
| 8 in (200 mm) | 100 | 480 |
| 12 in (300 mm) | 150 | 720 |
These figures are for normal-weight concrete. Metric values use nominal thickness (e.g., 100 mm × 2,400 kg/m³ = 240 kg/m²). For lightweight concrete (110 lb/ft³ / 1,760 kg/m³), multiply your thickness in feet by 110 or your thickness in metres by 1,760.
3. Total weight for common slab sizes
The table below gives total weights for slabs at the two most common thicknesses — 4 inches (100 mm) and 6 inches (150 mm) — using normal-weight concrete at 150 lb/ft³ (2,400 kg/m³):
| Slab size | 4 in thick | 6 in thick |
|---|---|---|
| 10 × 10 ft (3 × 3 m) | 5,000 lb / 2,268 kg | 7,500 lb / 3,402 kg |
| 12 × 12 ft (3.6 × 3.6 m) | 7,200 lb / 3,266 kg | 10,800 lb / 4,899 kg |
| 20 × 20 ft (6 × 6 m) | 20,000 lb / 9,072 kg | 30,000 lb / 13,608 kg |
| 24 × 24 ft (7.3 × 7.3 m) | 28,800 lb / 13,064 kg | 43,200 lb / 19,596 kg |
| 40 × 60 ft (12 × 18 m) | 120,000 lb / 54,431 kg | 180,000 lb / 81,647 kg |
For any other size, use the concrete weight calculator — enter length, width and thickness and pick your concrete type. The result appears instantly in both metric and imperial.
4. Why concrete weight matters
Knowing how much concrete weighs comes up in three practical situations, and getting the number wrong in any of them has real consequences.
Foundation and soil bearing
Every slab, wall or footing transfers its weight to the soil or structure below it. A 20 × 20 ft slab at 4 inches thick weighs about 20,000 lb — ten tons sitting on the ground. If the soil beneath is soft, that load can cause settlement. Structural engineers and building codes specify minimum soil bearing capacity for exactly this reason: the weight of the concrete is a significant part of the dead load the foundation must carry. The concrete footing calculator works out footing volume, and the weight calculator above converts that to a mass your engineer can check against the soil report.
Removing old concrete
Demolition and removal is where weight bites hardest. A standard ready-mix truck carries about 10 cubic yards — roughly 40,000 lb of concrete. Breaking up a driveway with a jackhammer produces a pile of rubble that weighs exactly the same as the slab did, just in smaller pieces, and dump trucks and disposal bins have weight limits. For a 24 × 24 ft driveway slab at 6 inches thick the rubble weighs about 43,000 lb. That is two full loads for a 20-ton capacity truck. Knowing the weight before the job prevents an underestimate on disposal cost — the second most common budget blowout after unexpected rebar.
Concrete truck loads
Ready-mix trucks are weight-limited for road transport. A fully loaded truck — drum plus concrete — is typically around 66,000 lb gross. With the drum at about 26,000 lb, that leaves room for roughly 40,000 lb of concrete, or about 9.9 cubic yards at 150 lb/ft³ (27 ft³ per yard). Most plants limit loads to 10 yards, and some jobs require a partial last load. Calculating the weight of the concrete you need tells you how many full trucks to order and whether you will have a short final load.
5. Worked example — a backyard patio
Say you are pouring a 12 × 16 ft patio at 4 inches thick, using normal-weight ready-mix.
- Volume in cubic feet: 12 × 16 × (4 ÷ 12) = 12 × 16 × 0.333 = 64 ft³
- Volume in cubic yards: 64 ÷ 27 = 2.37 yd³ (order 2.5 yd³ to allow for overage)
- Weight: 64 ft³ × 150 lb/ft³ = 9,600 lb (4,354 kg / 4.35 tonnes)
That is about 4.8 short tons sitting on the sub-base once cured. The ready-mix truck delivers the concrete wet; once placed and cured the weight barely changes (curing does not remove much mass — water is chemically bound, not evaporated).
Need the volume and bag count as well? The concrete volume calculator handles that — use both tools together to plan a pour completely.
6. Does reinforcement (rebar) change the weight?
Yes, but usually by less than you might think. A typical 4-inch residential slab uses #4 rebar (0.668 lb/linear ft) on a 12-inch grid. A 10 × 10 ft slab has about 210 linear feet of rebar — roughly 140 lb of steel in a 5,000 lb pour, which is about 3%. For most planning purposes the rebar weight is ignored or lumped in as a rounding margin. For structural or transport calculations where every pound matters, add the rebar weight separately using the pipe and bar weight calculator.
Common questions
- How much does concrete weigh per cubic yard?
- Normal-weight concrete weighs about 4,050 lb (1,837 kg) per cubic yard. One cubic yard is 27 cubic feet, and normal concrete is about 150 lb/ft³, so 27 × 150 = 4,050 lb — roughly 2 short tons.
- How much does concrete weigh per cubic foot?
- Normal-weight concrete weighs about 150 lb/ft³ (2,400 kg/m³). Lightweight concrete is around 110 lb/ft³ (1,760 kg/m³). Heavyweight concrete used for radiation shielding can reach 200 lb/ft³ (3,200 kg/m³).
- How much does a 4-inch concrete slab weigh per square foot?
- A 4-inch slab is one-third of a foot thick. At 150 lb/ft³ that is 150 × (4 ÷ 12) = 50 lb per square foot, or about 240 kg/m² in metric (using the nominal 100 mm equivalent at 2,400 kg/m³).
- How much does wet concrete weigh compared to cured concrete?
- Fresh (wet) concrete is very slightly heavier than fully cured concrete because some water is chemically bound during curing and a small amount evaporates. The difference is typically less than 2%, so for practical estimating you can use the same density figure — 150 lb/ft³ or 2,400 kg/m³ — for both.
- How many tons is a cubic yard of concrete?
- One cubic yard of normal-weight concrete weighs about 4,050 lb, which is roughly 2.025 short tons (US) or 1.84 metric tonnes. For rough site planning, two tons per yard is the common rule of thumb.
Reference & education only. Not professional, engineering, or code-compliance advice. Estimates are based on published model codes; local amendments and your Authority Having Jurisdiction (AHJ) govern. Always verify against the current adopted code and a licensed professional before doing work.
Last reviewed 2026-08.