Box / room
Also: rectangular prism, bed, trench, room
V = L × W × H
L = length, W = width, H = height or depth.
Example: A driveway 60 × 12 ft with 6 in of compacted base: 60 × 12 × 0.5 = 360 cu ft = 13.33 cu yd × 2.03 = 27.1 tons.
Quick answer: tons of road base = compacted cubic yards × 2.03. Compacted cubic yards = length × width (ft) × compacted depth (in) ÷ 324.
How to calculate road base
- Measure the length and width in feet.
- Choose the compacted depth in inches: the finished thickness after rolling or plate compacting.
- Compacted cubic yards = length × width × depth ÷ 324.
- Tons = compacted cubic yards × 2.03.
Tons = L (ft) × W (ft) × compacted depth (in) ÷ 324 × 2.03
A driveway 60 × 12 ft with 6 in of compacted base:
60 × 12 × 6 ÷ 324 = 13.33 cu yd. 13.33 × 2.03 = 27.1 tons.
Compacted vs loose: which figure to use
The Tennessee DOT Roadway Design Guidelines (Chapter 4) estimate aggregate base two ways:
| Depth you enter | Factor | lb per cu ft | Compaction allowance |
|---|---|---|---|
| Finished, compacted depth (default) | 2.03 tons per cu yd | 150.4 | None: already included |
| Loose depth as spread | 2,900 lb per cu yd (1.45 tons) | 107.4 | Don’t add one |
The ratio of the two factors (2.03 ÷ 1.45 = 1.4) means a cubic yard of compacted base takes about 1.4 cubic yards of loose material. That is why the compacted method is the safer way to order for a finished depth. Real figures depend on the mix and its moisture, so check your supplier’s weight if you buy by the ton.
How deep should road base be?
| Job | Common compacted depth |
|---|---|
| Walkway or patio base | 4 in |
| Shed or hot tub pad | 4–6 in |
| Home driveway, firm soil | 4–6 in |
| Home driveway, soft or clay soil | 6–8 in or more |
These are common residential practice, not code requirements. Commercial and public roads are designed by an engineer.
Road base names by region
The same kind of material, crushed stone graded down to fines that compacts hard, is sold under many names: crusher run, ¾ in minus, dense-graded aggregate (DGA), aggregate base course (ABC), 21A (Virginia), CA-6 (Illinois), Class 5 (Minnesota) and Class II base (California). Gradations differ, so ask the quarry for their base product for driveways.
Road base for different shapes
Area × depth
Also: square feet to cubic feet
V = A × d
A = area, d = depth or thickness.
Example: A 1,000 sq ft parking pad with 4 in of compacted base: 333 cu ft = 12.35 cu yd × 2.03 = 25.1 tons.
Sloped slab
Also: ramp, uneven depth, tapered bed
V = L × W × (h₁ + h₂) ÷ 2
L = length, W = width, h₁ and h₂ = depth at each end.
Example: A driveway section 50 × 12 ft, 8 in deep at the road and 4 in at the house: 50 × 12 × (0.667 + 0.333) ÷ 2 = 300 cu ft = 11.1 cu yd × 2.03 = 22.6 tons.
Cylinder
Also: round hole, post hole, tank, planter
V = π × r² × h
r = radius (half the diameter), h = height.
Example: A turnaround circle 20 ft across with 6 in of compacted base: π × 10² × 0.5 = 157 cu ft = 5.82 cu yd × 2.03 = 11.8 tons.
Worked examples
Shed pad
A 10 × 12 ft pad, 4 in compacted: 40 cu ft = 1.48 cu yd × 2.03 = 3.0 tons.
Ordering by loose depth
The same 60 × 12 ft driveway, but you plan to spread 6 in loose: 13.33 cu yd × 1.45 = 19.3 tons. It will compact to about 4.3 in, not 6.
- Top layer? Use the stone calculator for #57 on top, or the asphalt calculator for paving over the base.
Frequently asked questions
How much road base do I need?
Work out the compacted volume (length × width in feet × depth in inches ÷ 12, then ÷ 27 for cubic yards) and multiply by about 2 tons per compacted cubic yard. A 60 × 12 ft driveway with 6 in of base is 13.33 cu yd, or about 27 tons.
How many tons of road base are in a cubic yard?
About 1.45 tons per cubic yard loose (as it sits in the truck) and about 2.03 tons per cubic yard once compacted in place. Those are the figures the Tennessee DOT uses to estimate aggregate base. The calculator lets you pick either, or enter your supplier’s figure.
Should I use the compacted or the loose figure?
Use the compacted figure (the default) when your depth is the finished, compacted depth; that already allows for the material packing down. Use the loose figure only when your depth is the loose depth you will spread, and then don’t add a compaction allowance as well.
How deep should road base be for a driveway?
Residential gravel driveways are commonly built with 4–8 in of compacted base, more on soft or clay soil or for heavy trucks. Placing it in layers of about 4 in and compacting each one gives a firmer result. Follow your local requirements or an engineer for anything beyond a home driveway.
What is road base called where I live?
It goes by many names: crusher run, ¾ in minus, dense-graded aggregate (DGA), aggregate base course (ABC), 21A in Virginia, CA-6 in Illinois, Class 5 in Minnesota and Class II base in California. They are all mixes of crushed stone and fines that compact hard.
How much area does a ton of road base cover?
At 2.03 tons per compacted cubic yard, a ton covers about 40 sq ft at 4 in compacted, 27 sq ft at 6 in and 20 sq ft at 8 in.
Is this road base calculator free to use online?
Yes. The CalcWall Road Base Calculator is completely free and works online in any browser, on a phone, tablet or computer. There is nothing to download and no account to create, and the math runs right in your browser, so results appear as you type.