Road Base Calculator
Figure out how much road base to order for a driveway, pad, or paver bed. Enter the area in feet, the depth in inches, pick a material, and get cubic yards and US tons — with a compaction allowance so you do not come up short.
Example: with Length (ft) 50 · Width (ft) 12 · Depth (in) 6 · Material Crusher run / road base (~3,000 lb per yd3) · Compaction allowance (%) 15 → Tons to order: 19.17 US tons (order about 20).
- Cubic yards (loose)12.78 yd3 (11.11 yd3 compacted in place)
- Area covered600 sq ft at 6 in deep
Computed by the calculator below using its default values. Change any input to see your own numbers.
Volume = area × depth; tons = cubic yards × material weight ÷ 2,000. Base compacts 10–20% when rolled, so order loose volume accordingly.
How much base a driveway really needs
Road base (crusher run, ABC, 21A — names vary by region) is crushed rock with fines that locks together when compacted. A gravel driveway typically gets 4–8 inches of base; 6 inches handles cars, while trucks and RVs want 8 or more over soft soil. Paver patios usually get 4–6 inches, and shed pads 4 inches over fabric.
The math is simple: length × width × depth gives loose volume, and weight per cubic yard turns that into tons, which is how quarries sell it. The catch is compaction — a plate compactor or roller squeezes the loose lift down 10–20%, so a 6-inch finished layer takes roughly 7 inches of delivered material. That is what the compaction allowance covers.
How it’s calculated
Volume = length (ft) × width (ft) × depth (in) ÷ 12, converted to cubic yards at 27 cu ft per yard. Loose volume to order = compacted volume × (1 + compaction % ÷ 100). Tons = loose cubic yards × unit weight ÷ 2,000 lb. Unit weights used: crusher run 3,000 lb/yd3, #57 stone 2,700, bank-run gravel 2,800, RCA and coarse sand 2,600 — typical quarry figures.
Aggregate weights vary with moisture and rock type by roughly ±10%; confirm the tons-per-yard figure with your supplier before ordering.
Typical base depths by project
| Project | Base depth | Notes |
|---|---|---|
| Paver patio or walkway | 4–6 in | Plus 1 in bedding sand |
| Gravel driveway, cars | 4–6 in | Over compacted subgrade |
| Driveway, trucks/RV | 8–12 in | Place in 3–4 in lifts |
| Shed or hot-tub pad | 4 in | Geotextile fabric helps on clay |
| Under concrete slab | 4 in | Levels and drains the subgrade |
Common US residential practice; local codes and soft soils can require more.
Common mistakes
- Ordering the compacted volume with no allowance — the roller squeezes out 10–20%, leaving you a yard or two short.
- Measuring depth in feet instead of inches: a 6 ft entry inflates the order 12×.
- Using one big lift — base should be compacted in 3–4 inch lifts, so plan delivery and rental time for layers.
- Assuming all rock weighs the same: crusher run with fines runs about 1.5 tons/yd3, while clean #57 stone is closer to 1.35.
Frequently asked questions
How do I calculate road base tonnage?
Multiply length × width in feet, times depth in inches divided by 12, then divide by 27 for cubic yards. Add 10–20% for compaction, then multiply by the unit weight (about 3,000 lb per cubic yard for crusher run) and divide by 2,000 for US tons.
How many tons of base do I need per 100 sq ft?
At 4 inches deep, 100 sq ft needs about 1.42 loose cubic yards once you add a 15% compaction allowance — about 2.1 tons of crusher run. At 6 inches, figure roughly 3.2 tons.
Is a cubic yard of road base the same as a ton?
No. A cubic yard of compacted-grade crusher run weighs about 3,000 lb, so one yard is roughly 1.5 tons. Quarries usually sell by the ton; this calculator gives both numbers.
Why add a compaction allowance?
Base is delivered loose and then compacted 10–20% denser with a roller or plate compactor. If you order exactly the finished volume, the compacted layer ends up thinner than designed. 15% is a sensible default.
What is the difference between crusher run and #57 stone?
Crusher run includes stone dust and fines, so it packs into a hard, almost paved surface — ideal as a base. #57 is clean, uniform stone that drains well but stays loose, better as a top dressing or for drainage.