How Much Pea Gravel Under a 20x20 Deck?
A 20 by 20 foot deck covers 400 square feet. At 3 inches of pea gravel, plan on 3.70 cubic yards, or about 5.2 tons, which answers how much pea gravel under a 20x20 deck.
Volume and tonnage calculator →The math
- Area: 400.0 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic yards: 400.0 × 0.250 ÷ 27 = 3.70 yd³.
- Tons: × about 1.4 tons per yard = 5.2 tons.
The gravel calculator does this for any size.
Related: How Much Gravel Under a 20x20 Deck?
Pea gravel needed by depth
| Depth | Cubic yards | Tons of pea gravel | Tons +10% |
|---|---|---|---|
| 2 in | 2.47 | 3.5 | 3.8 |
| 3 in | 3.70 | 5.2 | 5.7 |
| 4 in | 4.94 | 6.9 | 7.6 |
| 6 in | 7.41 | 10.4 | 11.4 |
Building the deck base
Gravel under a deck blocks weeds, keeps the ground from turning to mud and lets water drain. Lay landscape fabric first, then about 2 to 3 inches of stone; there is no need to compact it the way you would a driveway base.
Related: How Much Pea Gravel Under a 12x20 Deck?
Before the stone goes in
Remove sod and roots, level the area and slope it slightly for drainage. Install edging so the stone stays inside the footprint.
Ordering and delivery
If you haul it yourself, a typical half-ton pickup should carry only about half a cubic yard of stone, well under what the bed looks like it can hold. Pea gravel is small and rounded, comfortable underfoot, and needs edging because it rolls. The scale ticket is the real weight; tons per yard here is a planning figure.
Planning the cost
Quarries and landscape suppliers set their own prices, and they change by region and season. Get the price per ton, the delivery fee and the minimum order. If two products will both work, compare cost per square foot at your depth rather than cost per ton.
Common mistakes
The most frequent problem is ordering for the finished depth without allowing for compaction, which can shrink a loose layer by 10 to 20 percent. Another is skipping fabric on soft soil and watching the stone vanish into the mud over the first wet season. Spreading everything in one thick layer instead of compacted lifts also leaves a soft, rutted surface.
Questions people ask
How many tons of pea gravel under a 20x20 deck?
About 5.2 tons at 3 inches deep.
How many yards of pea gravel under a 20x20 deck?
About 3.70 cubic yards.
How many tons of pea gravel are in a cubic yard?
Roughly 1.4 tons for planning, but suppliers vary with stone size and moisture.
Should I put landscape fabric under the stone?
On soft or clay soil, a woven geotextile keeps stone from sinking into the dirt and makes the layer last longer.
Related guides
- Gravel Under a Deck: Weeds, Drainage, and Depth
- How Much Does a Ton of Gravel Cover? Depth Chart
- Tons to Cubic Yards for Gravel: Conversion Chart
- Crushed Stone vs Gravel: Differences and Best Uses
- Geotextile Fabric for Driveways: Woven vs Nonwoven and How Much You Need
- Compacting a Driveway Gravel Base in Lifts
- How Much Crushed Stone Under a 20x20 Deck?
- How Much #57 Stone Under a 20x20 Deck?
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