How Much Gravel Under a 12x20 Deck?
How much gravel under a 12x20 deck: about 3.1 tons at 3 inches deep. The area is 240 square feet, which is 2.22 cubic yards at that depth.
Volume and tonnage calculator →The math
- Area: 240.0 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic yards: 240.0 × 0.250 ÷ 27 = 2.22 yd³.
- Tons: × about 1.4 tons per yard = 3.1 tons.
The gravel calculator does this for any size.
Related: How Much Crushed Stone Under a 12x20 Deck?
Gravel needed by depth
| Depth | Cubic yards | Tons of gravel | Tons +10% |
|---|---|---|---|
| 2 in | 1.48 | 2.1 | 2.3 |
| 3 in | 2.22 | 3.1 | 3.4 |
| 4 in | 2.96 | 4.1 | 4.6 |
| 6 in | 4.44 | 6.2 | 6.8 |
Stone for a deck
Under a deck, stone is a weed and moisture barrier rather than a structural layer. Slope the soil away from the house, lay fabric and spread 2 to 3 inches of washed stone that drains quickly.
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.
Buying the stone
Most quarries and landscape yards deliver by the ton; ask whether there is a minimum and a delivery fee, and where the driver can dump without damaging your lawn. Gravel is a broad label, so confirm whether the yard means crushed or rounded stone and whether it carries fines. Ask your supplier for their own tons-per-yard number, since stone source and moisture change it.
Measuring the area
Measure length and width in feet at a few points and use the largest figures, since real sites are rarely square. For odd shapes, split the area into rectangles and circles, work out each one and add them together. Depth is the number most people underestimate: drive a stake, run a level string and measure down to the dug-out surface in several spots.
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.
Questions people ask
How many tons of gravel under a 12x20 deck?
About 3.1 tons at 3 inches deep.
How many yards of gravel under a 12x20 deck?
About 2.22 cubic yards.
How many tons of 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 #57 Stone Under a 12x16 Deck?
- How Much Pea Gravel Under a 12x16 Deck?
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