Crushed Concrete Calculator
Recycled aggregate weighs less than the quarried stuff, so the same driveway takes fewer tons of it. Use a generic figure and you’ll over-order by roughly a seventh. This crushed concrete calculator applies the real weight of the grade you’re buying, adds the compaction allowance, and prices it.
Your result
What to order
7.1 tons (5.93 yd³) of 21AA crushed concrete for 400 sq ft at 4" deep
Yards sell recycled aggregate by the ton, so quote the tonnage and let them convert it to bucket loads.
- Area covered
- 400 sq ft at 4" finished
- Compaction allowance
- 4.94 yd³ loose becomes 5.93 yd³ ordered, once the 20% is added.
- Against virgin stone
- 21AA runs 2,400 lb a yard against about 2,800 for crushed limestone, so the same hole takes roughly 14% fewer tons.
- How this is worked out
- 400 sq ft × 4" ÷ 12 ÷ 27 = 4.94 yd³ + 20% = 5.93 yd³ × 2,400 lb ÷ 2,000 = 7.1 tons
What is crushed concrete?
It’s old concrete that has been broken up and put through a crusher. Demolished slabs, torn-out roadway, footings, curb. The steel gets pulled out with a magnet, the rest gets screened into sizes, and it comes out the far end graded like any other aggregate.
People also call it recycled concrete aggregate, or just RCA. In Michigan and much of the midwest you’ll hear it called 21AA, which is a grade rather than a product, though the two get used interchangeably at the counter.
The reason to work the tonnage out rather than guess is that this material behaves differently from the stone it replaces. It’s lighter, so a ton goes further. And it keeps compacting for weeks after you lay it, so the loose volume you order and the finished surface you end up with are two different numbers.
Calculate crushed concrete for a drive, pad or sub-base
Square feet × depth in inches ÷ 324 = cubic yards. Then add the compaction allowance, then multiply by the weight of your grade to reach tons. Three steps, and the middle one is the one everybody skips.
Take a drive 40 ft by 10 ft at 4 inches. That’s 400 sq ft, which comes to 4.9 cubic yards loose. Add the 20% and you order 5.9 yards, which in 21AA is about 7.1 tons.
Now the comparison worth seeing. That same hole in virgin crushed limestone would be 8.3 tons, because limestone weighs about 2,800 lb a yard against 2,400 for recycled. Order by a generic gravel figure and you’ve bought most of an extra ton you don’t need.
Grades: 21AA, 6A, 1" minus, and what each one does
Grades describe two things at once: the biggest stone in the mix, and whether the fines are still in there. That second part decides everything about how the material behaves once it’s down.
| Grade | Size | Lb per yd³ | What it is for |
|---|---|---|---|
| 21AA | 1" to fines | 2,400 | Driveway base and top course, packs to a hard crust |
| 6A | 1/4" to 1" | 2,300 | Clean washed stone for drainage and top dressing |
| 1" minus | 1" to fines | 2,400 | General base, sub-base and parking areas |
| Road base | 2" to fines | 2,500 | Deep sub-base under heavy traffic |
| Fines / screenings | Under 1/4" | 2,600 | Levelling course and paver bedding |
21AA is the one most people want. It runs from about an inch down to dust, and that spread is what lets it pack into a solid crust rather than staying loose. It’s the default for driveways across most of the midwest for exactly that reason.
6A is the opposite. It’s washed, so the fines are gone, which means water runs straight through and it never packs hard. Good around a drain, wrong under a car. Get those two the wrong way round and you’ll either have a drive that never firms up or a trench that holds water.
Depth by application: two inches through to eight
Four inches for a residential drive on decent ground. Six where trucks or trailers turn. Eight or more where the ground underneath is soft or stays wet. And two inches is a resurfacing job, not a build, so it only works over something already compacted.
| Job | Depth | Sq ft per yd³ | Sq ft per ton |
|---|---|---|---|
| top course | 2" | 162 | 135 |
| driveway | 4" | 81 | 68 |
| heavy use | 6" | 54 | 45 |
| sub-base | 8" | 41 | 34 |
Read the right-hand column and you can see why depth decides the bill. A ton covers 135 sq ft at two inches and only 34 at eight. That’s four times the material for the same patch of ground.
Whatever depth you pick, put it down in layers rather than all at once. Two four inch lifts with a compactor between them give a far firmer result than eight inches tipped and rolled once, because a plate compactor only reaches the top few inches.
Crushed concrete weight per yard, and why recycled comes in lighter
Between 2,300 and 2,600 lb a cubic yard depending on the grade, which is 1.2 tons or thereabouts for the common ones. Screenings sit at the heavy end because there are no big voids in them.
Here’s why it’s lighter than quarried stone. Concrete is aggregate held together by cement paste, and that paste is full of tiny air pockets. Crush it and those pockets stay. So a yard of recycled material has more air in it than a yard of solid limestone ever will.
That works in your favour on delivery. A tandem dump rated at 14 tons carries about 11.7 cubic yards of 21AA, against 10 of limestone. Same truck, same trip, more ground covered.
What crushed concrete costs
Roughly $15 to $30 a ton if you collect it, and $25 to $45 delivered. Call it half the price of virgin crushed stone, sometimes less. On a 7.1 ton driveway that’s a saving of a few hundred dollars before anyone has turned a shovel.
The reason it’s cheap is that somebody was going to pay to get rid of it. Demolition contractors pay tipping fees on clean concrete, so a recycler who takes it, crushes it and sells it on is earning at both ends. That economics is why the price holds up even when quarry prices move.
Delivery is charged per load, usually $75 to $150 within a normal radius. So one full load beats two half ones, and it’s worth rounding an order up to fill the truck rather than paying haulage twice for the same job.
Crushed concrete vs gravel on a driveway base
For a driveway base, crushed concrete usually wins. It packs harder because the cement fines re-bond, it costs about half as much, and being lighter you need fewer tons of it. Those three together are hard to argue with on a budget.
Gravel wins on looks and on drainage. Recycled material is grey, dusty and visibly made of broken slab, with the occasional flash of old paint or rebar hole. Nobody picks it for a front garden. And washed gravel drains better, because concrete fines eventually silt up.
So the honest split is this. Anywhere the surface is seen or has to drain freely, buy stone. Anywhere it’s a base, a sub-base or a working surface, buy recycled and spend the difference elsewhere. Plenty of drives use both: recycled underneath, a decorative course on top.
Where you should and should not use it
Good places: driveway base and surface, parking pads, road sub-base, backfill behind retaining walls, temporary haul roads, and bedding under pipe. All jobs where hard packing matters and looks don’t.
Bad places: anywhere plants have to grow. Crushed concrete leaches lime, which pushes soil pH up over time, so keeping it out of beds and away from anything acid-loving matters. It’s also wrong under a french drain, where the fines will clog the very voids you dug the trench for.
And check what you’re buying before it’s tipped. Clean recycled aggregate is graded and screened. The cheap stuff sometimes carries rebar ends, brick, asphalt lumps or worse, and once it’s on your drive it’s yours. Ask whether it’s screened and go and look at the pile if you can.
Crushed concrete questions
How much does a yard of crushed concrete weigh?
About 2,400 lb for 21AA, which is 1.2 tons. Screenings run heavier at 2,600 lb because the fines pack tighter. All of it is lighter than virgin crushed stone, which sits nearer 2,800 lb a yard.
How much is crushed concrete?
Roughly $15 to $30 a ton collected, and $25 to $45 delivered. That is about half what virgin crushed stone costs, and the gap is wider the closer you are to a recycling yard, because the material never travelled far.
Will crushed concrete harden?
Yes, and that is the point of it. Unreacted cement in the old concrete keeps hydrating, so a compacted layer knits together over a few weeks into a crust far firmer than loose gravel. Keep it damp while compacting and it sets harder still.
What is crushed concrete?
Old concrete, broken up and screened back into usable sizes. Demolished slabs, roadway, footings and kerb go through a crusher, the steel is pulled out magnetically, and what comes out is graded like any other aggregate.
What is crushed concrete used for?
Driveway base and surface, parking areas, road sub-base, backfill behind walls, and pipe bedding. Anywhere you want a hard-packing aggregate and the look of the stone does not matter, it does the same job as virgin material for less.
How much crushed concrete do I need?
Square feet × depth in inches ÷ 324 gives cubic yards, then add 20% for compaction and multiply by the grade weight. A 400 sq ft drive at 4 in works out at 5.9 cubic yards, or about 7.1 tons of 21AA.