Calculator 01 / 08
Gravel calculator
Measure each area, set the depth, and get the order quantity in cubic yards, tons and bags. The density is shown, sourced and editable — change it to your supplier's figure.
- Outputs
- yd³ · tons · tonnes · bags · cost
- Material basis
- Gravel · 105 lb/ft³ default, editable
- Method
- Formulas & sources
How the gravel calculation works
Gravel is measured by volume and usually sold by volume or weight. The calculator does it in order:
- Area. Each area you add is converted to square feet and summed.
- Volume. Area × depth gives cubic feet; ÷ 27 gives cubic yards.
- Allowances. Compaction (if any), then waste, are added as separate lines so you can see what each one costs you.
- Weight. The purchase volume × the loose density gives US tons and metric tonnes.
- Bags and cost. Bags are rounded up to whole bags; cost uses your own price.
Worked example: a garden path
A path 30 ft long and 4 ft wide, 3 in deep, with a 10% waste allowance:
| Area | 30 × 4 = 120 ft² |
|---|---|
| Volume | 120 × (3 ÷ 12) = 30 ft³ = 1.11 yd³ |
| + Waste 10% | 33 ft³ = 1.22 yd³ |
| Weight at 105 lb/ft³ | 33 × 105 = 3,465 lb ≈ 1.73 US tons |
| Bulk order | 1.5 yd³ (rounded up to the next half yard) |
| Or in 0.5 ft³ bags | 66 bags |
At 66 bags, most people would compare the bag price against a small bulk delivery. That comparison is the point of showing both.
Why the tons figure is an estimate
The default density is 105 lb/ft³ (about 1.42 US tons per cubic yard), the dry-gravel value in Engineering ToolBox source. A handbook range for gravel runs from about 1.23 to 1.62 tons per cubic yard source. Moisture, stone size, rock type and how the pile settles all move the number. If your supplier publishes a weight per yard or a conversion factor, type it into Density — that beats any general figure, including ours.
Buying by the ton? Take the cubic yards from here into the yards-to-tons converter and use the supplier's factor.
Choosing a depth
Depth does most of the work in this calculation: going from 2 in to 3 in adds 50% to the order. Decorative cover is usually thinner than a surface that will be walked or driven on. For driveways, which are built in layers, use the driveway calculator; for what the size numbers mean, see gravel types and sizes.
Questions
How do I figure out how much gravel I need?
Multiply length × width to get the area in square feet, multiply by the depth in feet (inches ÷ 12) to get cubic feet, then divide by 27 for cubic yards. Add a waste allowance, and convert to tons with your supplier's density if they sell by weight.
How many tons is a cubic yard of gravel?
It depends on the material. At the 105 lb/ft³ dry-gravel value we use by default, one cubic yard is about 1.42 US tons. A handbook range for gravel runs from about 1.23 to 1.62 tons per cubic yard. Use your supplier's figure when you have it.
Can I calculate an irregular area?
Yes. Split it into rectangles, circles and triangles, add each one as a separate area, and the calculator totals them. If you already know the area in square feet or square metres, use the ‘Known area’ option.
Should I add extra for waste?
Most people add a margin for spillage, uneven ground and edges. The default is 10% and you can change it. The allowance is shown as its own line so you can see how much it adds.