Gravel Calculator
This gravel calculator estimates how much gravel you need in cubic feet, cubic yards, pounds, and tons from the same measurements contractors use on site. Enter the project length and width in feet, depth in inches, the gravel density in pounds per cubic foot, and any waste allowance you want to carry for uneven ground, spillage, or compaction. The result helps when a supplier sells by the yard but a hauler quotes by the ton, or when you want a quick check before ordering stone for a driveway, path, drainage trench, or landscape bed. Gravel orders go wrong most often when depth is guessed instead of measured, or when people convert area to weight without accounting for density. This page keeps those steps in one place. It first finds the raw volume, then applies any waste percentage, then converts the adjusted volume into weight using the density you entered. If you do not have a supplier spec sheet yet, a common planning estimate is around 95 to 110 lb per cubic foot depending on gravel type, shape, and moisture.
Quick answer
The calculator starts with volume, because gravel fills space before it creates weight.
What this tells you
- •The calculator starts with volume, because gravel fills space before it creates weight.
- •Depth is entered in inches and converted to feet so the length, width, and depth units match.
- •Waste allowance increases the raw volume before weight is calculated, which helps cover uneven subgrade, settling, and minor overrun.
- •Density changes the tonnage a lot, so the same cubic yard count can produce different weight estimates for pea gravel, crushed stone, or wet material.
- •The tool returns both pre-waste volume and with-waste totals so you can compare a neat geometric estimate with the amount you may actually order.
How to Use
- 1Measure the length and width of the area in feet. Break irregular spaces into rectangles, calculate each rectangle, and add the totals before ordering.
- 2Enter the target depth in inches. Use compacted depth if you know the finished thickness you want after the gravel is spread and settled.
- 3Enter density in lb/ft3 if your supplier provides it. If not, use a reasonable planning estimate such as 100 or 105 lb/ft3 and confirm before purchase.
- 4Add an optional waste allowance if the job has sloped edges, soft spots, or material loss during hauling and spreading. Many small residential orders use 5% to 10%.
- 5Calculate the result, then review cubic yards and tons together. Order in the unit your yard or quarry uses, and round up to the supplier's delivery increment if needed.
How It Works
Formula
Depth(ft) = Depth(in) / 12
Cubic Feet = Length x Width x Depth(ft)
Cubic Yards = Cubic Feet / 27
Waste Multiplier = 1 + Waste% / 100
Adjusted Cubic Feet = Cubic Feet x Waste Multiplier
Weight(lb) = Adjusted Cubic Feet x Density
Weight(tons) = Weight(lb) / 2000The gravel formula in `lib/formulas/gravel-calculator.ts` uses a simple volume-to-weight flow. First it converts depth from inches to feet so all dimensions are compatible. Next it multiplies length, width, and depth to get cubic feet, then divides by 27 to get cubic yards. After that it applies the waste multiplier to the volume, not to the final tonnage separately, which keeps the math consistent. Finally it multiplies adjusted cubic feet by density in pounds per cubic foot and divides by 2,000 to estimate short tons. In plain language, the tool answers two questions in order: how much space the gravel must fill, and how much that volume should weigh for the material you chose.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Driveway gravel estimate
A 4 inch layer is 0.3333 feet deep. Multiply 20 x 10 x 0.3333 to get 66.67 cubic feet, then divide by 27 for 2.47 cubic yards. Adding 10% waste gives 73.33 cubic feet or 2.72 cubic yards. At 105 lb per cubic foot, that adjusted volume weighs 7,700 lb, which is 3.85 tons.
Patio base under pavers
Three inches converts to 0.25 feet. The raw volume is 12 x 16 x 0.25 = 48 cubic feet, which is 1.78 cubic yards. With a 5% waste factor, the total rises to 50.40 cubic feet. At 100 lb per cubic foot, the estimated order weight is 5,040 lb or 2.52 tons.
Garden path top-up
A 2 inch refresh layer equals 0.1667 feet. Multiply 30 x 4 x 0.1667 and the path needs 20 cubic feet before waste, or 0.74 cubic yard. After adding 8% for uneven spread and touch-up, the order becomes 21.60 cubic feet. Using a lighter 95 lb per cubic foot density produces 2,052 lb, which is about 1.03 tons.
Drainage trench fill
Eight inches is 0.6667 feet. The trench volume is 40 x 1.5 x 0.6667 = 40 cubic feet, and 40 divided by 27 is 1.48 cubic yards. With 12% waste, the adjusted quantity is 44.80 cubic feet or 1.66 cubic yards. Multiplying by 110 lb per cubic foot gives 4,928 lb, which rounds to 2.46 tons.
Play area pea gravel bed
Five inches equals 0.4167 feet of depth. The raw bed volume is 18 x 14 x 0.4167 = 105 cubic feet, which converts to 3.89 cubic yards. After a 7% allowance, the total becomes 112.35 cubic feet or 4.16 cubic yards. At 100 lb per cubic foot, the material weight is 11,235 lb, or 5.62 tons.
Resurfacing a 50 by 12 foot driveway
Lena wants a fresh 4 inch layer of crushed stone on her 50 by 12 foot driveway, and the quarry quotes by the ton. Four inches is 0.3333 feet, so the raw volume is 50 x 12 x 0.3333 = 200 cubic feet, or 7.41 cubic yards. She adds 10% because the edges have washed out unevenly, which lifts the order to 220 cubic feet or 8.15 cubic yards. The quarry has not given a density yet, so she keeps the default 100 lb per cubic foot: 220 x 100 = 22,000 lb, which is 11.00 tons. If the stone turns out to run 105 lb per cubic foot, the same volume weighs 11.55 tons, so she asks for the density before confirming the load.
Area one cubic yard of gravel covers by depth
How far a single cubic yard spreads at common depths, with the matching order for a 100 square foot area at the calculator's default density of 100 lb per cubic foot and no waste allowance. Halve the depth and the coverage doubles, because the volume is fixed at 27 cubic feet.
| Depth | One cubic yard covers | Cubic yards per 100 sq ft | Tons per 100 sq ft at 100 lb/ft3 |
|---|---|---|---|
| 1 inch | 324 sq ft | 0.31 | 0.42 |
| 2 inches | 162 sq ft | 0.62 | 0.83 |
| 3 inches | 108 sq ft | 0.93 | 1.25 |
| 4 inches | 81 sq ft | 1.23 | 1.67 |
| 5 inches | 64.8 sq ft | 1.54 | 2.08 |
| 6 inches | 54 sq ft | 1.85 | 2.50 |
| 8 inches | 40.5 sq ft | 2.47 | 3.33 |
| 12 inches | 27 sq ft | 3.70 | 5.00 |
Computed with the formula above. A cubic yard is 27 cubic feet and a short ton is 2,000 pounds (NIST Handbook 44, Appendix C), so coverage is 27 divided by the depth in feet, and one cubic yard at the calculator's default 100 lb per cubic foot weighs 2,700 lb, or 1.35 tons. The tons column uses that default density. Supplier bulk densities differ by stone type and moisture, so enter the supplier's figure when you have it.
Why yards and tons both matter
Many homeowners sketch a gravel project in square feet, then run into a supplier who sells in cubic yards and a hauler who quotes by the ton. That mismatch is normal. Volume tells you how much space the stone will fill. Weight tells you how much that filled space should weigh once you pick a material density. A useful order check is to compare both numbers before calling in the load.
A cubic yard is always 27 cubic feet, but the weight of that yard changes with the stone. At 105 lb per cubic foot, one cubic yard weighs 27 x 105 = 2,835 lb, or about 1.42 tons. If the gravel is closer to 95 lb per cubic foot, that same yard is about 1.28 tons. If it is 110 lb per cubic foot, the yard is about 1.49 tons. That is why a single yards-to-tons rule only works as a rough estimate.
Depth is the other number that changes the order quickly. A 100 square foot area at 2 inches deep needs only about 16.67 cubic feet before waste. The same area at 6 inches deep needs 50 cubic feet, which is exactly three times more material. Before you increase the project footprint, make sure the target depth matches the job, especially for driveways, trench stone, and paver base layers.
If you are planning a layered build, calculate each layer separately instead of averaging the densities together. For example, a driveway may use one depth for larger base rock and another for top gravel. Running each layer on its own gives a cleaner purchase list and makes supplier conversations easier.
The volume side of the formula rests on exact definitions. A cubic yard is 27 cubic feet and a short ton is 2,000 pounds (NIST Handbook 44, Appendix C), so the only estimate in the chain is density. Aggregate suppliers measure bulk density under ASTM C29/C29M, which reports loose and compacted values separately, and the two can differ for the same stone. The calculator applies one density to the loose volume you enter, so match that number to how the material is measured where you buy it.
Three things pull a real order away from the neat geometry. Density varies with stone type and moisture: angular crushed rock, rounded pea gravel, and a wet load fresh from the pile all weigh differently per cubic foot, which is why the tool asks for the number instead of assuming it. Spreading and compacting loose gravel shrinks its volume, and a common planning rule of thumb adds 10 to 20 percent for compaction, an allowance rather than a measured property, which belongs in the waste field. And suppliers sell either by weight or by the yard, so the two outputs here answer two different quotes. Round up to the delivery increment the supplier uses.
Common mistakes
- Entering depth in inches mentally but typing it as feet. A 4 inch layer is 0.3333 foot, not 4 feet, so a unit slip can multiply the order by 12.
- Using area alone to guess tons. Two projects with the same square footage can need very different tonnage if one is 2 inches deep and the other is 6 inches deep.
- Keeping the default density when the supplier's material is heavier or lighter. Density is the step that turns cubic feet into pounds, so it deserves a quick check.
- Skipping waste on jobs with irregular edges, drainage shaping, or soft subgrade. The neat rectangle math may be right while the delivered quantity still comes up short.
- Rounding down too early. Keep the calculator result through the end, then round according to the supplier's minimum order size or truck capacity.
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