What this calculator does
Find out how much gravel to order for a driveway, path or patio. You'll also see how much it weighs, how many bags that would be, and what it should cost. Suppliers sell gravel by volume (cubic yards or cubic meters) or by weight (tons or tonnes), and often quote both. To get either number, you need three things. They are the area you're covering, how deep the layer is, and the stone's density (how heavy a given amount of it is). You get the answer in both US and metric units.
Enter a rectangle by its length and width, or a circle by its diameter (the distance straight across). Then enter the depth. The calculator adds a little extra on top, because gravel packs down when it's tamped and some always gets lost while spreading. The density starts at a typical value you can change. Your supplier can tell you the exact figure for their stone.
Where it's used
Why this math matters outside the classroom:
- Driveway gravel. A 50 × 12 ft driveway topped 3 in deep needs 150 ft³, or about 5.56 cubic yards of gravel.
- Tons from yards. Quarries sell gravel by weight, so 5.56 yd³ at about 1.4 tons per cubic yard is close to 7.8 tons.
- Round fire-pit areas. A circular area 12 ft across and 4 in deep holds π × 6² × ⅓ ≈ 37.7 ft³ of pea gravel.
- Bagged gravel. For small jobs, homeowners divide the cubic feet by the 0.5 ft³ in a typical bag to count bags.
- Drainage trenches. Landscapers estimate the gravel for a 40 ft French drain trench 1 ft wide and 18 in deep, which is 60 ft³.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.G.A.2, 6.RP.A.3.d, 7.G.B.4. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose US units (feet, inches, pounds per cubic yard) or metric units (meters, centimeters, tonnes per cubic meter).
- Pick a rectangle or a circle, and enter its size and the depth of gravel.
- Change the density if your supplier gives you a figure. Then set the extra for compaction and waste.
- Enter your supplier's bulk price per ton or per cubic yard. If you're buying bags, enter the bag weight and price too. Clear the prices to skip the cost.
- Read the amount to order, its weight, the bulk and bag costs, and the bag count. The same numbers also appear in the other unit system.
What the inputs mean
- Depth
- How deep the gravel is once it's spread. Garden paths often use 2–3 inches. Driveways usually need 4 inches or more, sometimes laid in layers of different stone.
- Gravel density
- 2,800 lb per cubic yard is a typical figure for crushed stone. Loose, rounded gravel is usually lighter, and wet stone is heavier.
- Extra for compaction and waste
- Gravel shrinks as it packs down, and some is lost at the edges while you spread it. 5–15% extra is a common allowance.
- Bulk price (optional)
- Quarries and landscape yards charge either per ton or per cubic yard, so pick the one on your quote. The $45 per ton starting value is a stand-in, not a market price.
- Bag weight, if buying bags
- The bag count comes from weight, so it uses the density above. A 50 lb bag of typical crushed stone holds about half a cubic foot.
Formula and method
area = length × width or area = π × (diameter ÷ 2)² volume = area × depth volume to order = volume × (1 + allowance % ÷ 100) weight = volume to order × density 1 yd³ = 27 ft³ = 0.764554857984 m³; 1 US ton = 2,000 lb; 1 tonne = 1,000 kg bulk cost = tons (or yd³) to order × price; bags = weight ÷ bag weight, rounded up; bag cost = bags × price per bag
In the formulas, π (pi) is about 3.14, and the diameter is the distance straight across the circle. You enter depth in inches or centimeters. The calculator turns it into feet or meters first, so every number in the volume uses the same unit. Then it divides cubic feet by 27 to get cubic yards.
Density is how much a set amount of stone weighs, such as pounds per cubic yard. Weight is the volume times the density. In US units that gives pounds, and dividing by 2,000 gives US (short) tons. For tonnes, the calculator uses the exact value 1 lb = 0.45359237 kg.
Worked example
A 20 ft × 10 ft parking pad will get 3 inches of crushed stone at 2,800 lb per cubic yard. You add 10% extra.
- Area: 20 × 10 = 200 ft².
- Volume: 200 × (3 ÷ 12) = 50 ft³.
- Cubic yards: 50 ÷ 27 = 1.8519 yd³.
- With 10% extra: 1.8519 × 1.1 = 2.0370 yd³.
- Weight: 2.0370 × 2,800 = 5,703.7 lb, or 5,703.7 ÷ 2,000 = 2.85 US tons.
- Bulk at $45 per ton: 2.8519 × $45 = $128.33 before delivery.
- In 50 lb bags: 5,703.7 ÷ 50 = 114.07, which rounds up to 115 bags. At $5.50 each, that's $632.50.
Result: Order about 2.04 cubic yards (1.56 m³). It weighs roughly 2.85 US tons (2.59 tonnes) and costs about $128 in bulk, compared with $632.50 for 115 bags.
Understanding the result
Suppliers who sell by volume want the cubic yards or cubic meters. Those who sell by weight want the tons. Only the density links the two, so ask which one your quote uses.
Many suppliers deliver in set amounts, such as half or whole yards. Round up to the next amount they offer.
Bags make sense for small jobs, like topping up a path or filling a planter. Bagged stone usually costs much more per ton than bulk, so compare the two cost lines. Remember that bulk delivery adds a fee this calculator doesn't include.
Assumptions and limitations
- The layer is the same depth across the whole area.
- The density you enter is for the gravel as it's delivered.
- One percentage covers both packing down and spills.
- Density varies a lot between stone types, sizes and how wet they are, so the weight is an estimate.
- It doesn't handle sloped or odd-shaped areas. Split them into rectangles and circles, and add up the results.
- If you lay a base layer of different stone underneath, work it out separately with its own depth and density.
- Costs use the prices you enter. Delivery, landscape fabric, edging and tax aren't included.
Frequently asked questions
How many tons are in a cubic yard of gravel?
It depends on the stone. At the typical 2,800 lb per cubic yard used here, one cubic yard is 1.4 US tons. Lighter gravel might be closer to 1.2 tons, and dense crushed rock 1.5 or more.
How deep should gravel be?
Decorative beds and walking paths often use 2–3 inches (5–8 cm). Driveways usually need a deeper, packed-down base, often 4–8 inches in total. Your soil and how much traffic it gets matter too, so it's worth asking a contractor about a driveway.
How many bags of gravel do I need?
Find the weight to order, divide by the bag weight, and round up. One cubic yard of crushed stone at 2,800 lb is exactly 56 bags of 50 lb. So the 2.04 yd³ parking pad in the example needs 115 bags. Bags of lighter pea gravel each cover a little more.
How much does a yard of gravel cost?
Prices vary by stone type, region and season, so use your supplier's figure. To compare a per-ton quote with a per-yard quote, multiply the per-ton price by the stone's tons per yard. At $45 a ton and 1.4 tons per yard, that's $63 a yard.
Why add extra for compaction?
Loose gravel has air gaps between the stones. Tamping it or driving on it pushes the stones together, so the finished layer ends up thinner. Ordering a little extra keeps the final depth where you want it.
What is the difference between a ton and a tonne?
A US (short) ton is 2,000 pounds, or 907.18474 kg. A metric tonne is 1,000 kg, about 2,204.6 pounds, so it's roughly 10% heavier. The calculator shows both.
How this calculator is checked
Method: Prism volume (area × depth); weight = volume × density; exact US–metric conversion factors. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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