Gravel Calculator
Enter the area you are covering and how deep the stone goes. You get cubic yards for ordering by volume and tons for ordering by weight, with a compaction allowance if the layer is going to be rolled.
How much gravel do I need?
Multiply the area in square feet by the depth in feet, divide by 27 for cubic yards, then multiply by the density to get tons. A 20 ft x 10 ft driveway section at 4 in deep is 66.7 cu ft, which is 2.47 cubic yards, or about 3.5 tons at 1.4 tons per cubic yard.
Gravel you need
200 sq ft at 4 in deep is 2.96 cu yd, about 4.15 tons.
- Area covered
- 200 sq ft
- Volume
- 80 cu ft
- Weight
- 4.15 tons1.4 tons per cu yd
- Compaction added
- 20 %
The numbers above are a worked example for a 20 ft x 10 ft area at 4 in deep with a compaction allowance. Allow this page to run scripts in your browser to use your own dimensions, or follow the formula further down the page and do it by hand.
How the gravel calculator works, step by step
Gravel is quoted two ways, by the cubic yard and by the ton, and the two are not interchangeable without knowing the density of the specific rock. This page works out the volume exactly, because volume is geometry, then converts it to weight using a density you can change. Everything up to the last step is certain; only the last step depends on what came out of the quarry.
cubic yards = volume (cu ft) / 27
Worked example: a 20 ft x 10 ft area at 4 in deep
- Area: 20 x 10 = 200 sq ft
- Depth: 4 / 12 = 0.333 ft
- Volume: 200 x 0.333 = 66.7 cu ft
- With 20 % for compaction: 66.7 x 1.2 = 80 cu ft
- Cubic yards: 80 / 27 = 2.96 cu yd
- Tons at 1.4: 2.96 x 1.4 = 4.15 tons
Why tons and cubic yards do not convert cleanly
A cubic yard is a fixed volume. A ton is a fixed weight. Converting between them needs the density of the material, and for crushed stone that density is a property of the quarry, not of the industry. It depends on the rock type, how angular the crushing left it, the gradation, and how wet it is on the day it is loaded. Limestone, granite, trap rock and river gravel all weigh differently.
That is why this page treats density as an input with a sensible default of 1.4 tons per cubic yard rather than publishing it as a fact. Most dry crushed stone falls between 1.2 and 1.7 tons per cubic yard. Your supplier knows their own figure and will tell you if you ask, and wet material can be noticeably heavier than the same volume dry.
If a calculator anywhere gives you tons to two decimal places without asking which stone you are buying, it has quietly assumed a density. This one shows you the assumption and lets you correct it.
How deep should the gravel be?
| Use | Depth | Notes |
|---|---|---|
| Decorative stone in a bed | 2 to 3 in | Enough to hide the fabric and stay put |
| Garden path, foot traffic | 3 in | Over a compacted subgrade and fabric |
| Base under pavers | 4 to 6 in | Crushed and compacted in lifts, not rounded stone |
| Driveway, single layer | 4 in | Per layer; a new driveway is usually three layers |
| New driveway, full build-up | 8 to 12 in | Coarse base, intermediate, then surface stone |
A new gravel driveway is not one deep layer of one stone. It is a coarse base laid and compacted first, then a smaller intermediate layer, then the surface stone you actually see. Calculate each layer separately, because they are different products at different prices and each is compacted before the next goes down.
Compaction, and why the hole swallows more than you ordered
Crushed stone arrives loose and full of voids. Run a plate compactor or a roller over it and it loses roughly a fifth of its volume as the angular pieces lock together. If you order the finished compacted volume you will come up short, which is why the calculator adds 20 % by default when you tick the compaction box.
Rounded pea gravel and decorative stone are not compacted and do not need the allowance. Turn it off for those. The allowance is also separate from ordinary spillage and from stone that disappears into a soft subgrade; on a muddy site over soft ground, expect to lose more still, and lay a geotextile fabric first if you want the stone to stay where you put it.
Frequently asked questions
How many tons of gravel in a cubic yard?
About 1.4 tons for typical dry crushed stone, with most materials falling between 1.2 and 1.7. There is no single correct number: it depends on the rock, the gradation and the moisture. Ask the quarry what theirs weighs.
How much area does a ton of gravel cover?
At 1.4 tons per cubic yard, one ton is 0.71 cu yd, or 19.3 cu ft. Spread 3 in deep that covers about 77 sq ft, and at 4 in deep about 58 sq ft.
How much gravel for a 20 x 20 driveway?
400 sq ft at 4 in deep is 133 cu ft, or 4.94 cu yd, which becomes 5.93 cu yd once you add 20 % for compaction. That is about 8.3 tons for one layer. A full new driveway of three layers is roughly three times that.
What size gravel for a driveway?
Angular crushed stone, not rounded river gravel, because angular pieces lock together and rounded ones roll. A common build-up is a coarse 2 to 3 in base stone, then a 3/4 in crushed layer, then a surface of crusher run or 3/8 in stone. Rounded pea gravel makes a driveway that ruts and migrates.
Do I need landscape fabric under gravel?
Under a path or decorative stone, yes: it keeps the stone out of the soil and slows weeds. Under a load-bearing driveway or paver base, use a woven geotextile rated for separation rather than a thin garden fabric, and only over soft subgrade. It is there to stop the stone sinking into the mud, not to stop weeds.
Should I order by the yard or by the ton?
Order in whichever unit your supplier quotes, and use this page to check the other one. Trucks are loaded by weight, so tons is usually the billing unit, while the hole you are filling is a volume. Converting between them is exactly where estimates go wrong.
Source
The volume arithmetic on this page is the definition of a cubic yard and a cubic foot, so there is no coverage rate to go out of date. The density used to convert cubic yards to tons is deliberately not published as a fixed figure here, because it is a property of the specific stone rather than a standard: the default of 1.4 tons per cubic yard is a starting point, and the field is editable so you can enter the figure your own supplier quotes.