Bags of Pea Gravel for a 20x12 Patio

How many bags of pea gravel 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 pea gravel in 50-pound bags instead, figure about 125 bags, since pea gravel 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. At this size, a bulk delivery usually beats a cart full of bags once you count trips. Compare the bag price × 120 against a bulk quote for 3.4 tons delivered.

About pea gravel

Pea gravel is small, rounded stone, usually around 3/8 inch. It is comfortable to walk on and drains well, but it shifts under car tires and needs a solid edge to stay put.

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 rake smooth; rounded stone will not 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 pea gravel

Good uses:

Patios, walkways and dog runs
Play areas with proper depth and edging
Drainage around foundations when sized properly

Less suited to:

Driveways and steep paths, where it rolls and ruts
Under pavers as a base
Areas without edging

Quick reference numbers

Per inch over 100 sq ft: about 0.43 tons of pea gravel (0.31 cubic yards).
Per inch over 1,000 sq ft: about 4.3 tons.
Another size for comparison: a 10x20 area at 2 inches takes about 1.7 tons.
Weight used here: about 1.4 tons per cubic yard.

Common estimating mistakes

Measuring only the main rectangle. Aprons, turnouts and curved edges add real square footage.
Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
Ordering exactly the math. Uneven ground and spillage nearly always need a little more than the flat calculation.
Ignoring the base. A thin surface layer over soft soil fails early no matter how much material is on top.

Questions people ask

How many bags of pea gravel for a 20x12 patio?

About 120 bags of 0.5 cubic feet at 3 inches deep.

How many 50 lb bags of pea gravel 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.

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