Road Base Calculator
A road base calculator turns size and depth into tons at 1.5 tons per cubic yard: a 20 × 10 ft pad at 6 in needs 5.56 tons, or 6.11 with 10% extra.
What your order looks like
One bulk delivery is usually easier than hauling it yourself.
3.70 yd³ · 5.6 tons
50 wheelbarrow trips (2 cu ft each)
8 pickup loads (0.75 ton each)
1 small dump truck load (6 tons each)
Rules of thumb: A wheelbarrow trip is 2 cubic feet of heavy material, about 200 lb, a load most people can push. A pickup load is 0.75 ton, the payload of a full-size half-ton pickup (1,500 lb). A small single-axle dump truck carries about 6 tons.
Road base calculator formula
A road base calculator turns the size of a pad or driveway into tons of stone. The formula is tons = length × width × (depth in inches ÷ 12) ÷ 27 × 1.5.
Dividing by 27 converts cubic feet to cubic yards. The 1.5 is the weight in tons of one cubic yard of road base. Tick the box and the calculator adds 10 percent to cover the compaction and spread.
Worked examples
Example 1 is the default pad, 20 ft × 10 ft at 6 inches deep and $35 per ton.
- Volume: 20 × 10 × (6 ÷ 12) = 100 cubic feet
- 100 ÷ 27 = 3.704 cubic yards
- Tons: 3.704 × 1.5 = 5.56
- Cost: 5.56 × $35 = $194.44
- With 10 percent extra: 6.11 tons and $213.89
Example 2 is a 12 ft × 12 ft shed pad at 6 inches deep.
- Volume: 12 × 12 × 0.5 = 72 cubic feet
- 72 ÷ 27 = 2.667 cubic yards
- Tons: 2.667 × 1.5 = 4.00
- Cost: 4.00 × $35 = $140.00
- With 10 percent extra: 4.40 tons and $154.00
A small dump truck or a pickup load is often the delivery option for jobs this size. Ask the yard about minimums and delivery fees, because those can cost more than the stone on a small order.
Coverage per ton
At 1.5 tons per cubic yard, a ton of road base covers the following areas, net of any extra.
| Depth | Area covered by 1 ton | Tons per 100 sq ft |
|---|---|---|
| 2 in | 108 sq ft | 0.93 |
| 4 in | 54 sq ft | 1.85 |
| 6 in | 36 sq ft | 2.78 |
| 8 in | 27 sq ft | 3.70 |
Because road base is heavy, a thicker layer gets expensive fast. Go no deeper than the job needs.
Typical depths by project
| Project | Compacted depth |
|---|---|
| Paver patio or walkway base | 4 to 6 inches |
| Shed or small building pad | 4 to 6 inches |
| Driveway on firm soil | 4 to 6 inches, often more in total with layers |
| Base under a concrete slab | 4 inches is common, check the plan |
| Soft or wet ground | More, often with fabric or a coarser base below |
These are ranges that builders commonly use, not requirements. Your local code, your soil and the load decide the real number.
How to place it
- Strip the topsoil and organic material down to firm ground.
- Slope the finished surface so water runs off. A small fall of about 1/8 to 1/4 inch per foot is a common target.
- Spread the stone in layers and wet it lightly as you go.
- Compact each layer with a plate compactor until it feels firm and stops moving.
- Check the grade with a string line or a long level before you add paving or concrete.
How to measure
- Measure the length and width of the area, plus about 6 to 12 inches on each side for edges that need support.
- Measure depth after the soil is removed, so you know how much needs to be filled.
- For an odd shape, divide it into rectangles and triangles, and add the tons.
- For a driveway that narrows or widens, average the width.
Common mistakes
- Entering the finished depth when you want it to be loose depth. Loose stone settles when compacted.
- Not stripping topsoil first. Soft ground under the base lets it sink.
- Putting down the full depth in one pass.
- Forgetting drainage. Water sitting under the base is what breaks driveways in freezing weather.
- Using the wrong product for the job. Clean stone like #57 does not lock together the way road base does.
Related calculators
The crusher run calculator uses the same density, and the gravel driveway calculator handles a layered build. For a base under pavers, see the gravel base calculator.
Frequently asked questions
What is road base made of?
A blend of crushed stone with fine particles, such as stone dust, graded so it packs tightly. It goes by different names by region, including crusher run, quarry process, ABC, and dense-graded aggregate. Ask your supplier what they call it and what size it is.
How is road base different from crusher run?
They are close and often the same product under different names. Both are crushed stone with fines that lock together when compacted. The calculator uses 1.5 tons per cubic yard for both. The maximum stone size varies, so ask for a specification, not a name.
How deep should a road base layer be?
For a driveway or pad over firm soil, 4 to 6 inches compacted is common, and heavy loads or soft ground call for more. Paver patios use less, often 4 to 6 inches under the sand bed. Follow the local code or the paver maker's installation guide.
Do I need multiple lifts to compact road base properly?
For anything thicker than about 4 to 6 inches, yes. Spread, wet and compact one layer at a time, then add the next. A plate compactor only reaches so deep, so compacting a deep layer in one go leaves soft spots at the bottom.
Can road base go directly under concrete?
Yes, a compacted layer of road base or similar aggregate is a standard base under slabs, because it drains and gives even support. The amount depends on the slab's use and the soil. Check your plans or local code, and ask the concrete contractor.
Should I add waste when ordering road base?
Yes, a 10 percent allowance is a good habit. Loose stone compacts to a lower height, and some spreads beyond the edge. The calculator's 10 percent box adds this to the tonnage. If you are compacting a thick layer, you may want more.
Estimates only. Verify quantities with your supplier before purchasing.