How Much Road Base for 400 Square Feet?
How much road base for 400 square feet depends on depth. At 6 inches you need about 7.41 cubic yards, roughly 11.1 tons at 1.5 tons per yard. At 4 inches the order drops to 7.4 tons.
Volume and tonnage calculator →Road base for 400 sq ft by depth
| Depth | Cubic yards | Tons | Tons +10% |
|---|---|---|---|
| 4 in | 4.94 | 7.4 | 8.1 |
| 6 in | 7.41 | 11.1 | 12.2 |
| 8 in | 9.88 | 14.8 | 16.3 |
Working it out
- 400 sq ft × (6 ÷ 12) ft = 200.0 cubic feet.
- ÷ 27 = 7.41 cubic yards.
- × 1.5 tons per yard = 11.1 tons.
About road base
Road base (also called base rock, ABC, or Class 2 base in different states) is a graded mix of stone and fines made to compact into a load-bearing layer. Typical weight: 1.4 to 1.65 compacted tons per cubic yard.
Before the truck comes
- 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 road base
Good uses:
- Base under asphalt and concrete
- Gravel roads and drives
- Equipment and shed pads
Poor fit for:
- Drainage layers
- Decorative surfaces
- Surfaces that will stay uncompacted
Quick reference numbers
- Per inch over 100 sq ft: about 0.46 tons of road base (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.6 tons.
- Another size for comparison: a 8x16 area at 3 inches takes about 1.8 tons.
- Weight used here: about 1.5 tons per cubic yard.
Common estimating mistakes
- Mixing up cubic yards and tons. Yards are volume, tons are weight; convert with the product’s weight per yard.
- 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 road base for 400 square feet?
About 11.1 tons at 6 inches deep.
How many cubic yards of road base for 400 square feet?
About 7.41 yards at 6 inches.
How much road base for 400 square feet at 4 inches?
About 7.4 tons, or 4.94 cubic yards.
How much does a yard of road base weigh?
About 1.4 to 1.65 compacted tons.
Should I add extra?
Yes, about 10 percent is a common allowance.
Related guides
- Crushed Stone vs Gravel: Differences and Best Uses
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Much Does a Ton of Gravel Cover? Depth Chart
- How Much Road Base for 250 Square Feet?
- How Much Road Base for 300 Square Feet?
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