Bags of Pea Gravel for a 12x18 Patio

How many bags of pea gravel for a 12x18 patio: at 3 inches deep you need about 54.0 cubic feet, which is 108 bags of the common 0.5 cubic foot size. If your store sells pea gravel in 50-pound bags instead, figure about 112 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	18.0	36	38
2 in	36.0	72	75
3 in	54.0	108	112
4 in	72.0	144	150

How to figure it

Area: 12 × 18 = 216 sq ft.
Volume: 216 × (3 ÷ 12) = 54.0 cu ft.
Bags: 54.0 ÷ 0.5 = 108 bags (round up).

Bags or bulk?

A cubic yard is 27 cubic feet, so 54.0 cubic feet is 2.00 yards, about 2.8 tons. Past about a yard, bulk is usually less work and often less money. Compare the bag price × 108 against a bulk quote for 3.1 tons delivered.

About pea gravel

Because pea gravel is round, it never fully locks. Keep depths modest on walkways and patios so it does not feel like walking on a beach, and use edging.

Before you spread 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.

Where pea gravel fits

Best suited to:

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

Poor fit for:

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 3 inches takes about 2.6 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.
Mixing up cubic yards and tons. Yards are volume, tons are weight; convert with the product’s weight per yard.
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 bags of pea gravel for a 12x18 patio?

About 108 bags of 0.5 cubic feet at 3 inches deep.

How many 50 lb bags of pea gravel for 12x18?

About 112 bags at 3 inches.

How many 0.5 cubic foot bags are in a cubic yard?

54 bags.

How many cubic feet is a 12x18 patio at 3 inches?

About 54.0 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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