A cubic yard of normalweight concrete weighs about 3,780 to 4,050 lb — call it two short tons. The spread comes from density: NRMCA publishes 140 to 150 lb per cubic foot for normalweight concrete, and a cubic yard holds 27 cubic feet. At the usual working figure of 145 lb/ft³, a yard is 3,915 lb.
The weight chart
Everything below is the same arithmetic — density times volume — run at the ends and the middle of the range NRMCA gives for normalweight concrete in CIP 36.
| Volume | At 140 lb/ft³ | At 145 lb/ft³ | At 150 lb/ft³ |
|---|---|---|---|
| 1 ft³ | 140 lb | 145 lb | 150 lb |
| 1 yd³ (27 ft³) | 3,780 lb | 3,915 lb | 4,050 lb |
| 1 yd³, in tons | 1.89 tons | 1.96 tons | 2.03 tons |
| 3 ft³ (a full wheelbarrow) | 420 lb | 435 lb | 450 lb |
| 0.60 ft³ (an 80 lb bag, mixed) | 84 lb | 87 lb | 90 lb |
| 10 yd³ (a full truck) | 37,800 lb | 39,150 lb | 40,500 lb |
Two numbers are worth keeping in your head: 145 lb per cubic foot and 4,000 lb per cubic yard. Everything else is a multiplication. Need the volume first? The concrete slab calculator converts dimensions into cubic yards, and the cubic yards to tons converter does the same trip for aggregate.
Why the answer is a range, not a number
Concrete is aggregate, cement paste, water and air, and each one moves the density:
- The aggregate. It is 60 to 75% of the volume, so its specific gravity mostly sets the density. A granite or trap rock mix lands high in the range; a limestone mix lands lower.
- Air content. Entrained air is deliberate voids. Air-entrained concrete for freeze-thaw exposure carries several percent of air by volume, and every percent of air is a percent of weight that is not there.
- Water and paste. A wetter, pastier mix is a lighter mix, because water weighs 62.4 lb/ft³ against 165-plus for stone.
- Lightweight aggregate. Expanded shale, clay or slate changes the answer entirely — see below.
None of this is a reason to hunt for a more precise figure. If you need the real density of the concrete on your ticket, it is measured at the truck under ASTM C138, and your ready-mix supplier can tell you what their mix runs.
Fresh, cured, and the difference between them
Concrete loses a little weight as it cures and dries. NRMCA's CIP 36 puts numbers on it: equilibrium density — the in-service condition — is about 3 to 8 lb/ft³ below the fresh density measured on delivery. Over a cubic yard that is 80 to 215 lb, or 2 to 5%.
Lightweight concrete: 2,430 to 3,240 lb a yard
Structural lightweight concrete uses expanded shale, clay or slate aggregate fired in a rotary kiln to give it a porous structure. NRMCA's published range for equilibrium density is 90 to 120 lb/ft³, against 140 to 150 for normalweight — so a cubic yard runs 2,430 to 3,240 lb.
| Normalweight | Structural lightweight | |
|---|---|---|
| Density | 140-150 lb/ft³ | 90-120 lb/ft³ (equilibrium) |
| Per cubic yard | 3,780-4,050 lb | 2,430-3,240 lb |
| Typical use | Slabs on ground, footings, walls, pavement | Bridge decks, composite slabs on metal deck, topping slabs, tilt-up |
The point of paying more per yard is to take dead load out of the structure: smaller columns, smaller footings, less steel for the same capacity. Non-structural lightweight mixes made with perlite, vermiculite or pumice, or cellular concrete, go lighter still and are used for their insulating value rather than their strength.
Bags, barrows and what your back feels
Bagged mix confuses the weight question because the number on the bag is the dry mix. An 80 lb bag of QUIKRETE Concrete Mix yields 0.60 ft³, which at 145 lb/ft³ weighs about 87 lb once you have added the roughly 6 pints of water the data sheet calls for. So:
- A cubic yard from bags is 45 bags of 80 lb — 3,600 lb of dry mix to buy, carry, open and mix, before water.
- A full wheelbarrow is around 435 lb at 3 ft³. Two of those is a cubic foot short of a quarter yard, and your wrists know it.
- A 5 gallon bucket holds two thirds of a cubic foot — about 97 lb of concrete. That is why nobody fills one to the rim.
Past about a cubic yard, the weight is the argument for ready-mix, not the price.
Weight per square foot, by thickness
Slabs and decks are easier to think about per square foot than per yard: multiply the thickness in feet by 145 lb/ft³ and you have the dead load of the concrete itself, before reinforcement, finishes or anything standing on it.
| Thickness | Weight per ft² | Per 100 ft² | Cubic yards per 100 ft² |
|---|---|---|---|
| 4 in | 48 lb | 4,833 lb | 1.23 yd³ |
| 5 in | 60 lb | 6,042 lb | 1.54 yd³ |
| 6 in | 73 lb | 7,250 lb | 1.85 yd³ |
| 8 in | 97 lb | 9,667 lb | 2.47 yd³ |
| 10 in | 121 lb | 12,083 lb | 3.09 yd³ |
| 12 in | 145 lb | 14,500 lb | 3.70 yd³ |
A 4 in slab is about 48 lb per square foot; every additional inch adds roughly 12 lb. It is the fastest sanity check there is on a takeoff — if your tonnage and your square footage do not agree with this table, one of the two numbers is wrong.
Where the weight actually matters on site
- Elevated forms and shoring. A 6 in slab is 72 lb per square foot of dead load in concrete alone, before workers, tools or a pump line. Formwork and shoring are engineered for it.
- The delivery. Ten yards of concrete is nearly 40,000 lb of payload, and the drum, water and truck sit on top of that. Access, soft ground and axle limits are all weight problems.
- Picks and precast. A precast panel or a stair unit gets rigged by its weight: volume times density, then the sling angles. The load weight estimator runs that math for concrete and other materials.
- Steel is a rounding error, until it isn't. A #4 mat at 12 in on centre in a 20 by 20 ft slab adds about 520 lb against 19,300 lb of concrete. Run your own with the rebar calculator; on a heavily reinforced element the steel is worth counting.
- What you order versus what you place. NRMCA's TIP 8 lists why a paper volume comes up short at the truck — waste, spillage, loss of air content, settlement, form deflection, over-excavated subgrade. Weight per yard does not change; the number of yards does.
Bottom line
- A cubic yard of normalweight concrete: 3,780 to 4,050 lb, about two short tons.
- Per cubic foot: 140 to 150 lb, and 145 is the number to work with.
- Cured concrete is 3 to 8 lb/ft³ lighter than fresh; structural lightweight is 90 to 120 lb/ft³.
- Need the real figure for a submittal? It is measured at the truck under ASTM C138 — ask your supplier for their mix.