Ordering gravel is one of those jobs where guessing gets expensive either way. Order too little and you are waiting on a second delivery with half a driveway done. Order too much and you have a pile sitting in the yard. The good news is that the math is simple once you know the three measurements that matter and how gravel is sold.
What three measurements do you need?
- Length of the area, in feet.
- Width of the area, in feet.
- Depth of gravel you want, in inches.
For irregular shapes, break the area into rectangles, figure each one, and add them together. A tape measure or a measuring wheel works fine, and pacing it off is close enough for a first estimate.
How do you calculate cubic yards of gravel?
Gravel is usually priced and delivered by the cubic yard or by the ton. Start with cubic yards:
- Convert depth from inches to feet by dividing by 12.
- Multiply length × width × depth (all in feet). That gives cubic feet.
- Divide cubic feet by 27. That gives cubic yards.
Example: a driveway 100 feet long and 12 feet wide, with a 3 inch layer of rock.
- 3 inches ÷ 12 = 0.25 feet
- 100 × 12 × 0.25 = 300 cubic feet
- 300 ÷ 27 = about 11.1 cubic yards
How do you convert cubic yards to tons?
Many suppliers sell rock by weight. Crushed rock commonly weighs somewhere around 1.4 tons per cubic yard, though the exact number depends on the product and how wet it is. Clean drain rock and sand weigh a little differently, so it is worth asking your supplier for the figure they use.
Using about 1.4 tons per yard, the 11.1 cubic yard driveway above works out to roughly 15.5 tons.
Should you order extra for compaction?
Yes. Loose gravel settles and packs down when it is spread and compacted, and the ground underneath is rarely perfectly flat. Adding around 10 to 15 percent to your estimate is a common rule of thumb so you are not left short. For the example driveway, that brings the order to roughly 17 to 18 tons.
How deep should gravel be for common projects?
Depth makes the biggest difference in how much you need, so it is worth getting right. These are typical starting points, and soft or wet ground usually needs more:
| Project | Typical depth | Common rock |
|---|---|---|
| Refreshing an existing driveway | 2 to 3 inches | 3/4″ minus |
| New driveway base | 4 to 8 inches or more | 1-1/2″ or 3″ minus |
| New driveway top layer | 2 to 3 inches | 3/4″ minus |
| Walkway or path | 2 to 3 inches | 3/4″ minus, 1/4″ minus or pea gravel |
| Shed or patio base | 4 to 6 inches | 3/4″ minus |
| Parking pad or building pad | 6 inches or more | Larger base rock topped with 3/4″ minus |
Quick reference: coverage per cubic yard
One cubic yard covers roughly:
- About 160 square feet at 2 inches deep
- About 108 square feet at 3 inches deep
- About 81 square feet at 4 inches deep
- About 54 square feet at 6 inches deep
If your area is 500 square feet and you want 3 inches, that is roughly 500 ÷ 108, or a little under 5 cubic yards, before adding extra for compaction.
What else should you think about before ordering?
- Where the truck can dump. A dump truck needs firm ground, room to raise its bed and clearance from overhead wires and branches. Plan the drop spot before delivery day.
- Spreading. A large pile is a lot of wheelbarrow trips. Having it dumped close to where it will be used, or spread from the truck, saves a lot of work.
- Fixing the base first. If an existing driveway has soft spots or standing water, adding rock on top will not solve it. See our article on why gravel driveways get potholes.
- Choosing the right rock. The right product matters as much as the right amount. Our guide to gravel types explains which rock goes where.
Frequently asked questions
Crushed rock commonly weighs around 1.4 tons per cubic yard, but it varies by product and moisture. Ask your supplier for the number they use for the specific rock you are ordering.
At 2 inches deep, one ton of crushed rock covers roughly 100 to 120 square feet. At 3 inches, it covers roughly 70 to 80 square feet.
Usually, yes. Gravel compacts and the ground is rarely perfectly even, so adding about 10 to 15 percent helps you avoid coming up short partway through the job.
Yes, and it is often the best approach. A larger base rock provides strength on soft ground, and a 3/4″ minus top layer gives a smoother, firmer surface.
To skip the math, try our material calculator. You enter the size of your area and it estimates the amount for you.