Gravel Calculator – How Much Gravel Do I Need?
Whether you’re filling a driveway, pathway, or garden bed, our free gravel calculator tells you exactly how much gravel you need in cubic yards, cubic feet, and tons — no guessing required.
Gravel Calculator
Gravel Depth Guide
| Application | Recommended Depth |
|---|---|
| Garden Path | 2–3 inches |
| Driveway | 4–6 inches |
| Drainage | 6–12 inches |
| Decorative Bed | 2–4 inches |
How to Calculate How Much Gravel You Need
Gravel is sold by volume (cubic yards or cubic metres) or by weight (tons or tonnes), so the calculation runs in three steps: area, then volume, then weight.
2. Volume in cubic feet = Area x (Depth in inches / 12)
3. Cubic yards = Cubic feet / 27
The division by 27 catches people out. A cubic yard is 3 ft x 3 ft x 3 ft, which is 27 cubic feet, not 9.
Worked example: a driveway
A driveway 40 ft long and 12 ft wide, to be covered 4 inches deep:
- Area: 40 x 12 = 480 sq ft
- Depth in feet: 4 / 12 = 0.333 ft
- Volume: 480 x 0.333 = 160 cubic feet
- Cubic yards: 160 / 27 = 5.93 cubic yards
- Weight, at about 1.4 tons per cubic yard: 5.93 x 1.4 = 8.3 tons
Order about 10 percent extra to allow for compaction and uneven ground, so roughly 6.5 cubic yards here.
Gravel Weight and Coverage
| Measure | Typical value |
|---|---|
| 1 cubic yard of crushed stone | About 1.4 tons (2,800 lb) |
| 1 cubic yard of pea gravel | About 1.3 tons (2,600 lb) |
| 1 ton of gravel at 2 inches deep | Covers about 100 sq ft |
| 1 ton of gravel at 4 inches deep | Covers about 50 sq ft |
| 1 cubic metre of gravel | About 1.5 to 1.7 tonnes |
Weights vary with stone type and moisture. Wet gravel can be 10 to 15 percent heavier than the dry figures above, which matters if you are close to a delivery vehicle’s weight limit.
Recommended Depths
| Application | Depth | Notes |
|---|---|---|
| Garden path, foot traffic | 2 inches | Over landscape fabric |
| Decorative bed | 2 to 3 inches | Deeper suppresses weeds better |
| Driveway, single layer | 4 inches | Needs a compacted base |
| New driveway, full build | 8 to 12 inches | In layers: base, middle, top |
| Drainage or French drain | Varies | Use clean washed stone, no fines |
A proper driveway is built in layers rather than as one deep pour: a coarse base of larger stone, then a middle layer, then a finer top course. Each layer is compacted before the next goes down.
Common Gravel Mistakes
- Dividing cubic feet by 9 instead of 27. This triples your order and is the most expensive arithmetic error in the whole job.
- Ordering exactly what the calculator says. Gravel settles and compacts. Add about 10 percent.
- Skipping landscape fabric under decorative gravel. Without it the stone works its way into the soil and you top up every year.
- Using rounded pea gravel for a driveway surface. Rounded stone does not lock together and will rut under vehicle traffic. Angular crushed stone with fines compacts and stays put.
Frequently Asked Questions
How do I calculate how much gravel I need?
Multiply length by width to get the area in square feet, multiply that by the depth in feet (depth in inches divided by 12) to get cubic feet, then divide by 27 to get cubic yards. For a 40 x 12 ft driveway at 4 inches deep that is 480 x 0.333 = 160 cubic feet, which is 5.93 cubic yards.
How many cubic yards are in a ton of gravel?
Roughly 0.7 cubic yards, because one cubic yard of crushed stone weighs about 1.4 tons. The exact figure varies with stone type and moisture content: pea gravel is a little lighter at about 1.3 tons per cubic yard, and wet gravel can be 10 to 15 percent heavier than dry.
How much area does a ton of gravel cover?
About 100 square feet at 2 inches deep, or about 50 square feet at 4 inches deep. Coverage halves as you double the depth, so always decide your depth before estimating how much to order.
How much gravel do I need for a driveway?
For a top-up layer on an existing base, 4 inches is standard. For a completely new driveway, plan on 8 to 12 inches built up in compacted layers: coarse stone at the base, a middle layer, then a finer top course. A 40 x 12 ft driveway at 4 inches needs about 6 cubic yards, or roughly 8.3 tons.
Why do I divide by 27 to get cubic yards?
Because a cubic yard is 3 feet on every side, which is 3 x 3 x 3 = 27 cubic feet. Dividing by 9 instead is a common and costly error, since it would make you order three times too much gravel.
How much extra gravel should I order?
Add about 10 percent to your calculated figure. Gravel compacts once it is laid and raked, ground is rarely perfectly level, and running slightly short usually means paying a second delivery charge for a small top-up load.
What size gravel is best for a driveway?
Angular crushed stone works best because the pieces lock together under load. Crushed stone with fines, sometimes sold as crusher run or road base, compacts into a firm surface. Avoid rounded pea gravel as a driveway surface, since it shifts under tyres and forms ruts.