Gravel Calculator

How to calculate how much gravel you need

Gravel is ordered by volume (cubic yards) or by weight (tons), and you get both from three measurements. Measure the length and width in feet and the depth in inches, then:

Cubic yards = length (ft) × width (ft) × depth (in) ÷ 324
Tons = cubic yards × tons per yd³ (about 1.4 for gravel)

The 324 is 12 inches per foot × 27 cubic feet per cubic yard, so you never convert the depth by hand. The calculator above does the same math and also shows cubic feet, cubic meters, tonnes and 0.5 ft³ bags.

1. Measure the area. For odd shapes, split them into rectangles and add the results.
2. Choose the finished depth. Gravel compacts, so the loose depth you spread is a little more than the finished depth.
3. Pick the material. Weight per yard changes with stone type. The calculator has presets for mixed gravel, pea gravel, #57 crushed stone, crusher run, river rock and landscape rock.
4. Add 10% for compaction, spillage and an uneven base. Allow more on soft ground or for compacted base layers; ask your supplier how much their material compacts.

How much gravel do I need for common sizes?

Most people search for their own size: “gravel for a 10×10”, “20×20”, “1,000 sq ft”. This table answers the common ones at 4 in deep, a typical compacted base, using mixed gravel at 1.4 tons per yd³. Every figure comes from the same calculation the tool uses.

At 2 in deep, halve every figure. At 3 in, multiply by 0.75. At 6 in, multiply by 1.5: a 12 × 12 ft shed base at 6 in needs 2.67 yd³, about 3.73 tons.

How many tons are in a yard of gravel?

The calculator uses a typical planning weight of 1.4 tons (2,800 lb) per cubic yard for loose mixed gravel. It is not a measured value, so ask your supplier for the weight of their stone. Other stone types usually weigh a little more or less:

These are typical loose, dry planning weights, not measured values for your stone. Stone type, size and moisture all change the weight. Wet stone weighs more. If your quarry or yard quotes its own weight per yard, multiply the cubic yards by that figure instead.

How deep should gravel be?

The right depth depends on what the gravel has to carry. Depth is also the biggest driver of how much you order: 4 in uses twice as much as 2 in.

• Paths and decorative areas: use the depth your supplier or designer recommends, usually over landscape fabric.
• Patio and paver bases: Oregon State University Extension recommends 4–6 in of compacted crushed rock, thicker on soft clay or where it will be driven on.
• Base under a concrete slab: use the base depth your plans or local code specify, and size the concrete with the concrete slab calculator.
• Driveways: follow your supplier’s or designer’s spec, usually built in layers. Use the driveway gravel calculator for each layer.
• French drains and drainage trenches: use the stone depth your drain design specifies.

When a plan gives a finished depth, measure it after compaction. Loose gravel settles, which is one reason to add the extra 10%.

How much gravel per square metre?

Outside the US, gravel is sold by the tonne or by the cubic metre, often as 10 mm or 20 mm gravel. The calculator has a metric toggle. At 1.4 US tons per yd³, gravel is about 1.66 tonnes per m³.

For a 20 mm gravel driveway topping 50 mm deep, one tonne covers about 12 m². Bulk bag sizes differ by merchant, so check the stated weight or volume before you buy.

Metric jobs use the same logic with no 324: multiply length × width in metres by depth in metres. A 5 × 4 m area at 50 mm is 5 × 4 × 0.05 = 1 m³, about 1.66 tonnes, or 1.83 tonnes with 10% extra. A 6 × 6 m hardstanding at 100 mm is 3.6 m³, about 5.98 tonnes, or 6.58 tonnes ordered. If you think in inches, 2 in is 50.8 mm, 3 in is 76.2 mm and 4 in is 101.6 mm, so 50, 75 and 100 mm are close enough for ordering.

How much does a ton of gravel cover?

One ton of mixed gravel covers about 116 ft² at 2 in deep, 77 ft² at 3 in and 58 ft² at 4 in. Coverage per ton falls as the stone gets heavier, so a ton of crusher run covers less ground than a ton of #57 stone at the same depth.

To turn coverage into an order, divide your area by the figure in the column. A 400 ft² area at 3 in of mixed gravel needs 400 ÷ 77 ≈ 5.2 tons. The per-yard column is the same for every stone because it is pure volume; only the per-ton columns depend on weight.

Gravel per square foot, by weight

If you prefer to think in pounds, each square foot takes about 17.3 lb of mixed gravel at 2 in deep, 25.9 lb at 3 in, 34.6 lb at 4 in and 51.9 lb at 6 in. Crusher run is heavier: 19.8 lb at 2 in and 39.5 lb at 4 in. #57 stone sits slightly below mixed gravel at 16.7 lb at 2 in and 33.3 lb at 4 in. Multiply by your square footage and divide by 2,000 for tons.

Stone calculator: tons of stone for any area

The same calculator works as a stone calculator. Stone is ordered the same way as gravel, by area × depth to get cubic yards, then by weight per yard to get tons; only the weight per yard changes with the stone type. For a 10 × 20 ft area 3 in deep (1.85 yd³, 1.42 m³) the typical planning weights give:

The 12 × 24 ft area at 4 in is 3.56 yd³ (2.72 m³). These weights are typical planning values, not published standards; quarries weigh their own stone, so use the supplier’s tons per yard when it gives one. For clean angular stone see the crushed stone calculator, and for decorative stone the landscape rock calculator.

Which gravel type should I pick in the calculator?

Pick the preset that matches how the stone is made, not its color. Washed, single-size crushed stone has gaps between the pieces and drains well; crushed stone with fines packs hard; round stone rolls. The weight preset follows from that.

• Gravel (mixed), 1.4 tons per yd³: a sensible default when the supplier calls it “gravel” without a grade, or when you are comparing rough options.
• Crushed stone #57, 1.35: washed angular stone for drainage, French drains, under pavers and as the middle layer of a drive. Some suppliers sell a similar product as “3/4 in clean” stone.
• Crusher run / road base, 1.6: crushed stone mixed with stone dust. It compacts into a firm surface for pads, paths and driveway tops but drains more slowly.
• Pea gravel, 1.4: small round stone for walking surfaces; sized on the pea gravel calculator.
• River rock, 1.35, and landscape rock, 1.3: decorative stone sized on the river rock calculator.

Product names change by region, so ask two questions when you call: is it washed or does it contain fines, and what does a yard of it weigh? The first picks the preset; the second replaces it if the supplier has a figure. For a shed, the gravel pad is sized here, while a pad with concrete piers or footings belongs on the concrete footing calculator.

How much gravel for round and odd-shaped areas?

For a circle, the area is 3.1416 × radius², where the radius is half the diameter in feet. Choose Circle in the calculator and enter the diameter, or choose Known area and type the area in. At 4 in deep, mixed gravel works out like this:

A round fire pit area is a ring: work out the outer circle, subtract the pit. A 16 ft gravel circle around a 4 ft pit is 201.1 − 12.6 = 188.5 ft². At 3 in deep that is 1.75 yd³, about 2.44 tons, or 2.69 tons with 10% extra.

For an L-shape, split it into two rectangles. A 20 × 10 ft area plus a 10 × 8 ft leg is 280 ft², which at 4 in is 3.46 yd³ or 4.84 tons. Drawing one 20 × 18 ft box around the same shape gives 360 ft² and 6.22 tons, about 1.4 tons too much. For a triangle, use half of base × height.

How much gravel for a French drain or trench?

Treat the trench as a long box: length × width × depth of stone. For washed #57 stone at 1.35 tons per yd³, each 10 ft of trench needs:

A 50 ft trench, 12 in wide with 18 in of #57, is 75 ft³ gross: 2.78 yd³, about 3.75 tons, or 4.13 tons with 10% extra. The drain pipe takes a little of that volume. To subtract it, use the outside diameter from the pipe’s data sheet (corrugated pipe is wider than its nominal size): area in ft² = 3.1416 × (OD in inches ÷ 24)², times the trench length. Many drains are wrapped in fabric and topped with soil or decorative stone; only count the depth that is actually stone.

For a trench of any length, divide the per-10 ft figure by 10 to get tons per linear foot, then multiply by your length. A 12 in wide trench with 12 in of stone takes 0.05 tons per foot, so a 120 ft run around a house needs 6 tons, or 6.6 tons with 10% extra. Measure the length along the trench line after you mark it out, including any bends and the run to the outlet.

Should I buy gravel in bulk or bags?

Bags suit small jobs; bulk suits anything over about half a yard. A 0.5 ft³ bag holds 1/54 of a cubic yard, so one yard is 54 bags. A 4 × 4 ft pad at 4 in deep takes 11 bags, but a 10 × 10 ft base takes 67. Ask local suppliers about minimum loads and delivery charges, which vary by area. When you compare prices, convert both to the same unit with the tons to cubic yards converter.

Bag sizes vary by brand and store, so count from the volume printed on the bag:

If a bag lists only its weight, divide the job’s total pounds by the bag weight instead. Damp stone weighs more than dry, so a bag sold by weight holds a little less stone than the table suggests; round up.

Common mistakes when ordering gravel

Most gravel orders go wrong on units, not on the arithmetic. These are the errors that cost the most, with the size of each one.

• Entering depth in feet instead of inches. The 324 formula expects inches. A 10 × 10 ft area at 3 in needs 0.93 yd³; type 3 ft by mistake and you get 11.11 yd³, twelve times too much.
• Ordering tons when you worked out yards. A yard of gravel weighs about 1.4 tons, so ordering “4.94 tons” for a 4.94 yd³ job (a 20 × 20 ft area at 4 in) brings only about 3.53 yd³, roughly 29% short.
• Using the wrong stone weight. The same 20 × 20 ft area at 4 in is 6.67 tons of #57 stone but 7.9 tons of crusher run. Pick the matching preset, or use your supplier’s weight per yard.
• Rounding the depth down. Going from 3 in to 4 in on a 10 × 10 ft base raises the order from 0.93 to 1.23 yd³, a third more. Decide the finished, compacted depth before you call for quotes.
• Skipping the extra. On a 20 × 20 ft base at 4 in, the 10% allowance is about 0.69 tons. Without it, compaction and spillage usually leave low spots that need a second, small delivery.
• Measuring odd shapes as one rectangle. Split L-shapes and curves into rectangles and add them; a bounding rectangle over-orders, and guessing under-orders.

Gravel calculator vs pea gravel, driveway and river rock calculators: which one to use

This general gravel calculator covers mixed gravel, #57 crushed stone, crusher run and landscape rock for bases, slabs, paths and drains. Switch to a more specific tool when the job has its own rules:

• Pea gravel calculator: patios, paths, dog runs and play areas, with 0.5 ft³ bag counts and shallow-depth guidance for round stone.
• Driveway gravel calculator: layer-by-layer tonnage for base stone, #57 and crusher run, with driveway size tables.
• River rock calculator: decorative beds, borders and dry creeks, where the depth is set by the size of the stones.
• Tons to cubic yards: when a supplier quotes by the ton and you need to compare it with a price per yard.
• Aquarium gravel calculator: pounds of gravel or sand for a fish tank from its length, width and bed depth.