How Much Gravel for 400 Square Feet?
How much gravel for 400 square feet depends on depth. At 4 inches you need about 4.94 cubic yards, roughly 6.9 tons at 1.4 tons per yard. Going to 6 inches raises it to 10.4 tons.
Volume and tonnage calculator →Gravel for 400 sq ft by depth
| Depth | Cubic yards | Tons | 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 |
Working it out
- 400 sq ft × (4 ÷ 12) ft = 133.3 cubic feet.
- ÷ 27 = 4.94 cubic yards.
- × 1.4 tons per yard = 6.9 tons.
About gravel
Plain gravel is a loose term. Yards use it for rounded bank or river stone as well as for crushed rock, so ask whether the load is washed, crushed or a mix before you lock in a tonnage. Most suppliers will quote 1.3 to 1.5 tons per yard for this material.
Ordering checklist
- Measure odd shapes in pieces. Split curves and L-shapes into rectangles and add them.
- Add a margin. About 10 percent covers compaction and low spots.
- Bulk or bags. Bulk delivery is the practical choice here.
- Prep first. Remove sod, compact the subgrade and set edging before the stone arrives.
Use the volume and tonnage calculator for any other size.
Good and poor uses for gravel
Good uses:
- Rural driveways and lanes where low upfront cost matters
- Drainage areas and around downspouts
- Temporary access while a site is under construction
Poor fit for:
- Steep slopes, where loose stone washes downhill
- Spots plowed often, since plows push gravel into the lawn
- Areas next to doors, because stone tracks inside
Quick reference numbers
- Per inch over 100 sq ft: about 0.43 tons of gravel (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.3 tons.
- Another size for comparison: a 20x25 area at 3 inches takes about 6.5 tons.
- Weight used here: about 1.4 tons per cubic yard.
Mistakes that throw off the order
- Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
- 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.
- Assuming every supplier uses the same weight. Two yards selling the same product name can quote different tons per yard.
Questions people ask
How many tons of gravel for 400 square feet?
About 6.9 tons at 4 inches deep.
How many cubic yards of gravel for 400 square feet?
About 4.94 yards at 4 inches.
How much gravel for 400 square feet at 2 inches?
About 3.5 tons, or 2.47 cubic yards.
How much does a yard of gravel weigh?
About 1.3 to 1.5 tons.
Should I add extra?
Yes, about 10 percent is a common allowance.
Related guides
- How Much Does a Ton of Gravel Cover? Depth Chart
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Much Does a Ton of Gravel Cover? Depth Chart
- How Much Gravel for 250 Square Feet?
- How Much Gravel for 300 Square Feet?
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