Bags of Crushed Stone for a 8x20 Patio
How many bags of crushed stone for a 8x20 patio: at 3 inches deep you need about 40.0 cubic feet, which is 80 bags of the common 0.5 cubic foot size. If your store sells crushed stone in 50-pound bags instead, figure about 83 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 | 13.3 | 27 | 28 |
| 2 in | 26.7 | 54 | 56 |
| 3 in | 40.0 | 80 | 83 |
| 4 in | 53.3 | 107 | 111 |
How to figure it
- Area: 8 × 20 = 160 sq ft.
- Volume: 160 × (3 ÷ 12) = 40.0 cu ft.
- Bags: 40.0 ÷ 0.5 = 80 bags (round up).
Bags or bulk?
A cubic yard is 27 cubic feet, so 40.0 cubic feet is 1.48 yards, about 2.1 tons. At this size, a bulk delivery usually beats a cart full of bags once you count trips. Compare the bag price × 80 against a bulk quote for 2.3 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.
Laying it down 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.
When to choose crushed stone
Best suited to:
- Driveway top courses and parking pads
- Shed and hot tub bases
- Backfill behind walls when a clean size is used
Less suited to:
- 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 10x20 area at 4 inches takes about 3.5 tons.
- Weight used here: about 1.4 tons per cubic yard.
Common estimating mistakes
- Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
- Measuring only the main rectangle. Aprons, turnouts and curved edges add real square footage.
- 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.
Questions people ask
How many bags of crushed stone for a 8x20 patio?
About 80 bags of 0.5 cubic feet at 3 inches deep.
How many 50 lb bags of crushed stone for 8x20?
About 83 bags at 3 inches.
How many 0.5 cubic foot bags are in a cubic yard?
54 bags.
How many cubic feet is a 8x20 patio at 3 inches?
About 40.0 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 8x16 Patio
- Bags of Crushed Stone for a 8x18 Patio
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