How Much Pea Gravel for a 20x18 Patio?
How much pea gravel for a 20x18 patio: at 3 inches deep you need about 3.33 cubic yards, which is roughly 4.7 tons at 1.4 tons per yard. The patio covers 360 square feet, so every inch of depth adds about 1.11 yards.
Volume and tonnage calculator →The math for a 20x18 patio
- Area: 20 × 18 = 360 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic feet: 360 × 0.250 = 90.0 cu ft.
- Cubic yards: ÷ 27 = 3.33 yd³.
- Tons: × 1.4 = 4.7 tons.
The volume and tonnage calculator does this for any size.
Pea gravel needed by depth
| Depth | Cubic yards | Tons (approx.) | Tons +10% |
|---|---|---|---|
| 2 in | 2.22 | 3.1 | 3.4 |
| 3 in | 3.33 | 4.7 | 5.1 |
| 4 in | 4.44 | 6.2 | 6.8 |
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. Weight per yard is a planning number; the scale ticket at the yard is the real one.
Preparing the patio
Remove sod, level the area with a slight slope away from the house, and lay landscape fabric if weeds are a concern. Edging keeps loose material inside the patio footprint. For foot traffic and furniture, the depths in the table above are a reasonable starting range.
Ordering tips
- Round up. Compaction and uneven ground eat material. Adding about 10 percent is common.
- Delivery size. 5.1 tons fits in a single typical dump truck load; small loads may carry a delivery fee. See how many tons of gravel in a dump truck.
- Bulk vs bags. At this size bulk delivery is usually the practical choice.
- Where it drops. Have the truck dump as close to the patio as firm ground allows.
Where pea gravel fits
Good uses:
- Patios, walkways and dog runs
- Play areas with proper depth and edging
- Drainage around foundations when sized properly
Think twice 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 4 inches takes about 3.5 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.
- Forgetting that compaction shrinks loose material. A loose 4-inch spread of a dense-graded stone may finish closer to 3 inches after rolling.
- 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.
Questions people ask
How many tons of pea gravel for a 20x18 patio?
About 4.7 tons at 3 inches deep, or 5.1 tons with 10 percent extra.
How many cubic yards is a 20x18 patio at 3 inches?
About 3.33 cubic yards.
How much does a cubic yard of pea gravel weigh?
Usually around 1.3 to 1.5 tons, depending on stone size, fines and moisture.
How deep should pea gravel be for a patio?
The table above shows 2 to 4 inches. Shallower depths suit top dressing; deeper depths suit new installs and heavier use.
How many square feet is 20x18?
360 square feet.
Related guides
- How Much Does a Ton of Gravel Cover? Depth Chart
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Many Tons of Gravel in a Dump Truck? Loads and Coverage
- How Much Pea Gravel for a 20x14 Patio?
- How Much Pea Gravel for a 20x16 Patio?
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