Solid volume, then weight, then the volume it becomes
Three different volumes get confused on a demolition job and only the first one is a measurement. The slab in the ground is solid volume: twenty by twelve feet at four inches is eighty cubic feet, which is 2.96 cubic yards. Multiply that by a density near 145 pounds per cubic foot and you have 11,600 pounds, or 5.8 tons. Then break it, and the pieces stop touching each other. At 50 percent swell those eighty cubic feet become 120, which is 4.44 loose cubic yards. Same material, same weight, half again the space.
The number that matters at the container is the ratio of those two: 11,600 pounds spread across 4.44 loose yards is about 2,610 pounds per cubic yard, or 1.31 tons. Against a two ton allowance that is 1.53 cubic yards of box. In a ten yard container, the weight is gone when the box is about 15 percent full.
Swell is a genuine variable, not a fudge factor
How much broken concrete bulks up depends almost entirely on piece size. A slab taken out in slabs, stacked flat on a trailer, swells barely at all. The same slab reduced to fist-sized rubble by a breaker swells least of all once it settles, because small pieces fill each other's gaps. It is the middle that swells most: irregular pieces a foot or two across, thrown rather than placed, with rebar sticking out of them holding the pile apart. That is the normal outcome of a residential demolition and it is why the default here is 50 percent.
| How it comes out | Rough swell | Why |
|---|---|---|
| Sawn and lifted in whole panels | Near zero | The pieces still stack flat |
| Broken into large irregular chunks | 50 to 75 percent | Nothing sits against anything else |
| Broken small, then loaded with a bucket | 35 to 50 percent | Small pieces fill the voids |
| Rubble with rebar left in | Highest of all | The steel props the pile open |
The swell field is the one worth arguing with, because it decides the volume half of the container question and nothing else on the page does.
Density, and why it is the least interesting input
Normal weight concrete sits close enough to 145 pounds per cubic foot that arguing about it is not worth the time. Asphalt is in the same neighbourhood. Pavers on a sand bed come out lighter because you are lifting units and bedding rather than a monolith, and lightweight structural concrete is genuinely different but is not what a driveway is made of. If you want to check, weigh a piece you have already broken off and measure it. Where the real error lives is thickness: a driveway measured at four inches at a control joint and poured at six across the middle is fifty percent more of everything, and that error dwarfs anything density can do.
Clean concrete is a different material to a disposal facility
Rubble with no wood, no soil, no plastic and no trash in it is often handled on a separate stream from mixed demolition waste, because it can be crushed and sold again as aggregate. Whether that stream exists near you, what it accepts, whether rebar disqualifies a load, and what either one costs are questions for the facility and for your hauler. It is worth asking before the container arrives rather than after, because the answer changes how the material is stacked and whether the wood framing goes in the same box.
What this page cannot see
It cannot tell you what the slab is holding up. A garage floor is usually just a floor, but a slab can be integral with a footing that is under a wall, and separating those is a structural question that belongs to an engineer rather than to arithmetic. It cannot see reinforcement you have not found, thickness that varies, or an older slab poured on top of an even older one. And it cannot tell you what is buried under the flatwork, which is the reason to call 811 before the first cut. For the material going back in afterwards, the concrete slab calculator covers the pour and the asphalt driveway calculator covers hot mix. If the demolition also produces dirt, the excavation volume calculator handles bank and loose yards for soil, which swells differently. If you plan to move the rubble yourself, the debris hauling trips calculator turns this tonnage into loads, hours and a comparison against a container.
Questions people ask
How much does a concrete slab weigh per square foot?
At a density near 145 pounds per cubic foot, a four inch slab is about 48 pounds per square foot, a five inch slab about 60, and a six inch slab about 73. That means ten square feet of four inch slab is roughly a quarter of a ton, and a 240 square foot patio is close to six tons. The number people underestimate is thickness rather than density, so measure at a cut edge before trusting any of it.
How many cubic yards is a broken up concrete slab?
Take the solid volume and add the swell. Twenty by twelve feet at four inches is 2.96 cubic yards solid; broken with 50 percent swell it occupies about 4.44 loose cubic yards. The gap matters because the container is rented by loose volume and the tonnage is charged against the solid weight, and only one of those two numbers went up.
What size dumpster do I need for concrete?
Almost always a small one, and the reason is weight rather than space. Broken concrete runs somewhere near 1.3 tons per loose cubic yard, so a two ton allowance is used up at about a yard and a half of material. A ten yard box in that situation is around 15 percent full when it has to go. This is why haulers put concrete in small containers and why ordering a larger one to be safe achieves nothing.
Can I put broken concrete in a regular dumpster with the rest of the demolition?
That is a question for the hauler and for the facility they take it to, and it is worth asking before the box arrives. Clean rubble is often handled separately from mixed demolition waste because it can be crushed and reused, and mixing it with wood, drywall and packaging can remove that option for the whole load. The calculator will tell you the tonnage either way; what it costs on each stream is a rate you get from them.
How many pickup loads is a concrete slab?
Divide the total weight by the payload figure printed on your own vehicle, which the calculator will do if you enter it. The answer is usually more loads than the volume suggests, because six tons of rubble occupies about four and a half cubic yards and no half-ton pickup is going to move that in two trips. What any vehicle may carry on a road is set by its ratings and by your state, not by whether the material fits in the bed.