Bags of Crushed Stone for a 20x12 Patio
How many bags of crushed stone for a 20x12 patio: at 3 inches deep you need about 60.0 cubic feet, which is 120 bags of the common 0.5 cubic foot size. If your store sells crushed stone in 50-pound bags instead, figure about 125 bags, since crushed stone weighs roughly 104 pounds per cubic foot.
Volume and tonnage calculator →Bag count by depth
| Depth | Cubic feet | 0.5 cu ft bags | 50 lb bags (approx.) |
|---|---|---|---|
| 1 in | 20.0 | 40 | 42 |
| 2 in | 40.0 | 80 | 83 |
| 3 in | 60.0 | 120 | 125 |
| 4 in | 80.0 | 160 | 166 |
How to figure it
- Area: 20 × 12 = 240 sq ft.
- Volume: 240 × (3 ÷ 12) = 60.0 cu ft.
- Bags: 60.0 ÷ 0.5 = 120 bags (round up).
Bags or bulk?
A cubic yard is 27 cubic feet, so 60.0 cubic feet is 2.22 yards, about 3.1 tons. Past about a yard, bulk is usually less work and often less money. Compare the bag price × 120 against a bulk quote for 3.4 tons delivered.
About crushed stone
Most quarries sell crushed stone by a size number or a screen size. Clean crushed stone drains well; stone with fines packs harder but sheds water more slowly.
Install tips for a patio
- Dig and level. Remove sod and set the base slightly below the surrounding grade.
- Edge it. Steel, plastic or stone edging keeps material in place.
- Spread in layers. Rake to depth, then tamp or wet and compact.
- Buy a few extra. Grab 5 to 10 percent more bags for settling and touch-ups.
The volume and tonnage calculator handles other sizes and depths.
Good and poor uses for crushed stone
Works well for:
- Driveway top courses and parking pads
- Shed and hot tub bases
- Backfill behind walls when a clean size is used
Think twice 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 15x30 area at 2 inches takes about 3.9 tons.
- Weight used here: about 1.4 tons per cubic yard.
Mistakes that throw off the order
- Ignoring the base. A thin surface layer over soft soil fails early no matter how much material is on top.
- Ordering exactly the math. Uneven ground and spillage nearly always need a little more than the flat calculation.
- Measuring only the main rectangle. Aprons, turnouts and curved edges add real square footage.
- Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
Questions people ask
How many bags of crushed stone for a 20x12 patio?
About 120 bags of 0.5 cubic feet at 3 inches deep.
How many 50 lb bags of crushed stone for 20x12?
About 125 bags at 3 inches.
How many 0.5 cubic foot bags are in a cubic yard?
54 bags.
How many cubic feet is a 20x12 patio at 3 inches?
About 60.0 cubic feet.
When does bulk make more sense?
Usually once the job passes about a cubic yard, or when you would need more than a few car trips.
Related guides
- How Much Does a Ton of Crushed Stone Cover?
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Much Does a Ton of Gravel Cover? Depth Chart
- Bags of Crushed Stone for a 16x30 Patio
- Bags of Crushed Stone for a 20x10 Patio
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