The First Delivery: Not Enough
My driveway project started with a guess. The driveway was roughly 20 feet long and 10 feet wide. I wanted 4 inches of gravel. I eyeballed it, ordered 2 cubic yards, and felt pretty good about myself.
The truck dumped the pile. I spread it out. Covered about two-thirds of the driveway. The last third was bare dirt staring back at me.
Second delivery fee: $75. The gravel itself was only $45 per cubic yard. I paid more for the truck to come back than for the material I needed.
The Math I Should Have Done First
The formula is three multiplications and one division. That's it.
My driveway: 20 ft × 10 ft × 4 inches deep. But you can't mix feet and inches — convert the depth to feet first: 4 inches ÷ 12 = 0.333 feet.
Gravel is sold in cubic yards. One cubic yard = 27 cubic feet.
I needed 2.47 cubic yards. I ordered 2. No wonder I came up short.
The Second Delivery: Too Much
Overcompensating from my first mistake, I ordered 2 full cubic yards for the remaining third. That's roughly double what I needed for the gap. The extra gravel sat in a pile next to my garage for six months. My neighbor started calling it "the monument."
The right order would have been 1 cubic yard — maybe 1.25 with a compaction buffer. But I was frustrated and rounded up aggressively. Lesson learned: math is cheaper than pride.
The Compaction Factor Nobody Mentions
Loose gravel settles. Rain, traffic, and gravity compress it over time. Most gravel suppliers recommend ordering 10-15% extra to account for compaction. Some materials compact more than others — crushed stone settles more than river rock because the angular pieces lock together tighter.
For my 2.47 cubic yards, adding 10% compaction buffer: cubic yards. Round up to 3. That's what I should have ordered from the start.
Always round up to the nearest half or whole cubic yard. Suppliers don't deliver in decimals, and a small surplus beats a second delivery fee every time.
How Thick Should Your Gravel Be?
This depends on what's going under it and what's driving on it:
| Application | Recommended Depth | Notes |
|---|---|---|
| Walkway / path | 2-3 inches | Foot traffic only |
| Patio base | 4 inches | Under pavers or flagstone |
| Driveway | 4-6 inches | Vehicle traffic, may need base layer |
| Heavy vehicle area | 8-12 inches | Trucks, RVs, equipment |
For driveways, many contractors recommend a two-layer approach: 3-4 inches of larger crushed stone (#2 or #3) as a base, topped with 2-3 inches of finer gravel (#57 or pea gravel) for a smooth surface. The base layer handles drainage and load-bearing; the top layer handles aesthetics and tire comfort.
The Third Time: Getting It Right
For a small side path — 15 ft × 3 ft × 2 inches deep — I finally did the math first.
cubic feet. Divide by 27: cubic yards. Add 10% compaction: cubic yards. I ordered half a cubic yard.
Perfect coverage, tiny surplus, zero second trips. The gravel calculator does this in about 5 seconds. I spent $150 in extra delivery fees learning what a calculator could have told me for free.
It's the same lesson as shopping math — the numbers aren't hard, but eyeballing them costs real money.
Frequently Asked Questions
How much gravel do I need for a driveway?
Measure length × width × depth (in feet), divide by 27 to get cubic yards, then add 10-15% for compaction. A typical single-car driveway (20 ft × 10 ft × 4 inches) needs about 2.5-3 cubic yards. A two-car driveway (20 ft × 20 ft × 4 inches) needs 5-6 cubic yards.
How do you calculate cubic yards?
Multiply length × width × depth in feet to get cubic feet, then divide by 27 (since 1 cubic yard = 27 cubic feet). Make sure all measurements are in the same unit — convert inches to feet by dividing by 12 before multiplying.
How thick should gravel be for a driveway?
4-6 inches total for standard passenger vehicles. Ideally, use a two-layer system: 3-4 inches of larger crushed stone as a base for drainage and stability, topped with 2-3 inches of finer gravel for a smooth driving surface. Heavy vehicles (trucks, RVs) may need 8-12 inches total.