How Much Gravel for an 18x20 Carport?
How much gravel for an 18x20 carport: about 6.2 tons at 4 inches deep and 9.3 tons at 6 inches, over 360 square feet.
Volume and tonnage calculator →The math
- Area: 360.0 sq ft.
- Depth in feet: 4 ÷ 12 = 0.333 ft.
- Cubic yards: 360.0 × 0.333 ÷ 27 = 4.44 yd³.
- Tons: × about 1.4 tons per yard = 6.2 tons.
The gravel calculator does this for any size.
Related: How Much Crushed Stone for an 18x20 Carport?
Gravel needed by depth
| Depth | Cubic yards | Tons of gravel | Tons +10% |
|---|---|---|---|
| 4 in | 4.44 | 6.2 | 6.8 |
| 6 in | 6.67 | 9.3 | 10.3 |
| 8 in | 8.89 | 12.4 | 13.7 |
Carport pad tips
Most steel carports can anchor into a compacted gravel pad with auger or rebar anchors. Make the pad slightly larger than the frame and keep it level so the frame goes up square.
Related: How Much Crusher Run for an 18x20 Carport?
How deep
Four inches works on firm ground for cars. Six inches is safer for trucks, heavy SUVs or soft soil.
Getting it delivered
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. 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.
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.
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.
Questions people ask
How many tons of gravel for an 18x20 carport?
About 6.2 tons at 4 inches or 9.3 at 6 inches.
Can a carport sit on gravel?
Many metal carports anchor into compacted gravel with ground anchors; check your kit.
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
- 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 for a 12x24 Carport?
- How Much Crusher Run for a 12x24 Carport?
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