This page answers one size only: a gravel driveway 12 feet wide by 20 feet long. The answer below is for that size only. To change the size, depth, or waste allowance, use the Gravel Driveway Calculator.
Gravel driveway 12 by 20 ft: summary
| Item | Value |
|---|---|
| Driveway width | 12 ft |
| Driveway length | 20 ft |
| Area | 240 sq ft |
| Depth used | 4 in |
| Volume before waste | 80 cu ft (2.96 cu yd) |
| Waste allowance | 10% |
| Order volume | 3.26 cu yd |
Worked example in full
Step 1 — Area: 20 ft × 12 ft = 240 square feet.
Step 2 — Depth in feet: 4 in ÷ 12 = 0.333 feet.
Step 3 — Volume in cubic feet: 240 sq ft × 0.333 ft = 80 cubic feet.
Step 4 — Volume in cubic yards: 80 ÷ 27 = 2.96 cubic yards.
Step 5 — Waste allowance: 2.96 × 1.10 = 3.26 cubic yards.
Answer for this size only: order 3.26 cubic yards of gravel for a 12 by 20 ft driveway at 4 inches deep with a 10% waste allowance. This result was verified against the Gravel Driveway Calculator using length 20 ft, width 12 ft, depth 4 in, and waste 10%.
Frequently asked questions
Is 3.26 cubic yards the answer for any gravel driveway?
No. It is the answer for a 12 by 20 ft driveway at 4 inches deep with 10% waste only. A different size, depth, or waste allowance gives a different answer.
What if I want a different depth?
Repeat the steps above with your depth in feet, or enter your size and depth in the Gravel Driveway Calculator.
Why add a waste allowance?
The allowance covers uneven ground, compaction, and spillage, so the delivered volume matches the finished driveway. The calculator lets you change the percentage.
Method note
This is a planning calculation for the stated size and depth only. It assumes a flat rectangular driveway at a uniform 4-inch depth. Confirm the depth, base, and delivery volume with your supplier before ordering.