How Much Does 21 Tons of Crushed Stone Cover?
How much does 21 tons of crushed stone cover depends on how deep you spread it. At about 1.4 tons per cubic yard, 21 tons is roughly 15.0 cubic yards. Spread 4 inches deep, that covers about 1,215 square feet. Go thinner and it covers more; go deeper and it covers less.
Volume and tonnage calculator →How the coverage is figured
- Tons to cubic yards: 21 ÷ 1.4 = 15.0 yd³.
- Cubic yards to cubic feet: × 27 = 405 cu ft.
- Divide by depth in feet: at 4 inches (0.333 ft), 405 ÷ 0.333 = 1,215 sq ft.
Coverage of 21 tons at different depths
| Depth | Square feet covered | Square yards |
|---|---|---|
| 2 in | 2,430 | 270 |
| 3 in | 1,620 | 180 |
| 4 in | 1,215 | 135 |
| 6 in | 810 | 90 |
About crushed stone
Crushed stone has fractured faces, so the pieces interlock when compacted. That is why it holds a driveway or pad shape better than round stone of the same size. Weight runs about 1.35 to 1.5 tons per cubic yard, so treat the table as a planning range rather than an exact figure.
Putting 21 tons to use
21 tons will usually take two or more truck loads, though legal limits vary by truck and state. Spread from the pile with a loader, skid steer or wheelbarrow, then rake to depth before compacting if the material calls for it.
- Check depth as you go. Stakes marked at the target depth help keep the spread even.
- Expect some loss. Compaction and uneven ground use more than the flat-math figure. Keep about 10 percent in reserve.
- Ask about moisture. Wet material weighs more, so a ton of it covers less.
To run your own numbers, use the volume and tonnage calculator.
Good and poor uses for crushed stone
Good uses:
- Driveway top courses and parking pads
- Shed and hot tub bases
- Backfill behind walls when a clean size is used
Poor fit for:
- Barefoot areas, since angular stone is rough
- Play areas
- Places that need a smooth rolling surface for wheels
Quick reference numbers
- Per inch over 100 sq ft: about 0.43 tons of crushed stone (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.3 tons.
- Another size for comparison: a 20x25 area at 3 inches takes about 6.5 tons.
- Weight used here: about 1.4 tons per cubic yard.
Where estimates go wrong
- Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
- Mixing up cubic yards and tons. Yards are volume, tons are weight; convert with the product’s weight per yard.
- Ordering exactly the math. Uneven ground and spillage nearly always need a little more than the flat calculation.
- Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
Questions people ask
How many cubic yards is 21 tons of crushed stone?
About 15.0 cubic yards at 1.4 tons per yard.
How many square feet does 21 tons of crushed stone cover at 4 inches?
About 1,215 square feet.
How many square feet does 21 tons cover at 2 inches?
About 2,430 square feet.
How much does a yard of crushed stone weigh?
About 1.35 to 1.5 tons.
Will 21 tons fit in one truck?
It depends on the truck. Single-axle dump trucks often carry under 10 tons and tandems around 13 to 16; your supplier will know their limits.
Related guides
- How Much Does a Ton of Crushed Stone Cover?
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Many Tons of Gravel in a Dump Truck? Loads and Coverage
- How Much Does 19 Tons of Crushed Stone Cover?
- How Much Does 20 Tons of Crushed Stone Cover?
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