Formula
Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12. Cubic yards = cubic feet ÷ 27. Example: a 10 ft × 4 ft path at 3 in deep needs 10 cubic feet, or 0.37 cubic yards.
How to use it, step by step
Measure the path or area, including any edging you will fill. Choose depth by use: 2–3 inches suits a garden path, while a driveway needs a deeper, compacted base layer plus a surface layer — this calculator gives the volume for one layer, so calculate base and surface separately if you are building a driveway. Order by cubic yards for bulk delivery, and ask the supplier for the weight in tons if your vehicle or driveway has a weight limit.
Worked example in detail
A path 20 ft long and 3 ft wide at 3 inches deep needs 20 × 3 × 3 ÷ 12 = 15 cubic feet, or 0.56 cubic yards. At 2 inches it needs only 10 cubic feet; at 4 inches, 20 cubic feet. Depth is the easiest number to get wrong, and a path that looks thin after spreading usually needed one more inch, not more area.
What affects real gravel needs
Compaction reduces volume after spreading and rolling, so add about 10% for a driveway base. Gravel migrates into soft soil without landscape fabric underneath, so fabric saves gravel over time on paths. Angular gravel locks together and stays put better than rounded pea gravel, which rolls and spreads. For drainage, use a coarser grade and a deeper layer, and never use gravel to hide a drainage problem that needs a proper outlet.
Frequently asked questions
How many tons is a cubic yard of gravel?
It varies by stone type, size and moisture, typically around 1.2–1.5 tons per cubic yard. Always confirm with your supplier, because ordering by tons from a volume figure you guessed is a common source of short deliveries.
Do I need landscape fabric under gravel?
For paths on soil, yes — it stops gravel sinking into mud and weeds coming up. For drainage trenches, use a permeable fabric that lets water through, not plastic sheeting.
Can I use this for a driveway?
For volume, yes, but a driveway needs a compacted sub-base as well as a surface layer. Calculate each layer separately and add them.