This calculator works out how much material you need to fill a patio or walkway area. You enter the length and width of the space in feet (or meters) and the depth of the gravel, sand, or stone base in inches, and it returns the volume in cubic yards and cubic feet. The first result, cubic yards, is the number you take to a supplier to order bulk material.
Formula
The volume of a rectangular slab is length times width times depth. The only tricky part is converting inches to feet and then to cubic yards.
Volume (ft³) = Length (ft) × Width (ft) × Depth (in) ÷ 12
Volume (yd³) = Volume (ft³) ÷ 27
Combining those gives the formula used in the calculator:
Volume (yd³) = (L × W × D) ÷ 324
Where:
- L = length of the patio or walkway in feet
- W = width in feet
- D = depth of the material layer in inches
- 324 = 27 (cubic feet per cubic yard) × 12 (inches per foot)
If you measure in meters, the same logic works: volume in cubic meters = L (m) × W (m) × D (m). Most landscape suppliers in the US sell bulk aggregate by the cubic yard, so the calculator’s first output is the one you’ll order with.
Worked Example
Using the default values from the calculator: a 40 ft long by 25 ft wide patio with a 3-inch gravel base.
- Convert depth to feet: 3 in ÷ 12 = 0.25 ft
- Find cubic feet: 40 × 25 × 0.25 = 250 ft³
- Convert to cubic yards: 250 ÷ 27 = 9.26 yd³
The calculator shows 9.26 yd³ and 250 ft³, matching the hand calculation. For a walkway that is 30 ft long, 3 ft wide, and 4 in deep, the same steps give 30 × 3 × 0.333 = 30 ft³, or 1.11 yd³.
How to Use the Result
The cubic yard figure is what you use when ordering bulk gravel, sand, or crushed stone from a landscape yard. Most suppliers deliver in whole or half yards, so you’ll likely round up to 10 yd³ for the example above. For bagged material, divide the cubic feet result by the bag’s coverage (usually printed on the bag, e.g., 0.5 ft³ per bag) and round up to the next whole bag.
For a paver base, you typically need two layers: a 4–6 inch layer of crushed stone (the base) and a 1-inch layer of sand (the setting bed). Run the calculator twice, once for each depth, to get separate quantities. For a concrete slab, the depth is the slab thickness (usually 4 inches for a walkway, 6 inches for a patio that will hold a hot tub or heavy vehicle).
Choosing the Right Material and Depth
The depth you enter depends on what you’re building:
- Paver base (crushed stone): 4–6 inches for patios, 6–8 inches for driveways
- Sand setting bed under pavers: 1 inch
- Gravel bed for a walkway (no pavers): 2–3 inches
- Concrete slab: 4 inches for foot traffic, 6 inches for vehicles
Material type matters too. Crushed stone compacts well and is the standard base. Pea gravel does not compact and shifts underfoot, so it’s better for a loose walkway than a paver base. Sand for a setting bed should be coarse, not fine play sand, which washes out and doesn’t lock pavers.
Common Mistakes and How to Avoid Them
The most frequent error is mixing units. If you measure the area in feet but the depth in inches, you must convert before multiplying. The calculator handles that, but if you do it by hand, always write the units down.
Another mistake is forgetting that cubic yards are a volume, not a weight. A yard of gravel weighs about 1.4 tons, but the weight varies by material. If you’re ordering by the ton, ask the supplier for the conversion factor for the specific aggregate.
Over-excavation is also common. The volume calculation assumes a flat, rectangular hole. If your site slopes or has curves, break it into rectangles and add the volumes. Add 5–10% for compaction and spillage—crushed stone settles about 10% when compacted, so you’ll need more than the loose volume.
Costs and Ordering
Bulk material is priced per cubic yard, and delivery is usually a flat fee. Bagged material costs more per volume but is easier for small projects. To estimate cost, multiply the cubic yards by the per-yard price from your local supplier. For a 10 yd³ order, even a $10 per yard difference changes the total by $100, so it pays to compare.
If you’re having material delivered, know that most trucks carry 10–15 cubic yards. For a small walkway, you might order a fraction of a yard, but many suppliers have a minimum delivery charge. Bagged material avoids that but is more expensive per cubic foot.
Frequently Asked Questions
How many bags of paver base do I need?
Divide the cubic feet result by the coverage per bag, which is printed on the bag (often 0.5 ft³ for a 50 lb bag of paver base). Round up to the nearest whole bag. For the 250 ft³ example, you’d need 500 bags—that’s why bulk delivery is usually better for anything over a few square feet.
Can I use this calculator for a circular patio?
No, this calculator is for rectangular areas. For a circle, use the formula π × radius² × depth. For an irregular shape, divide it into rectangles and triangles, calculate each, and add them together.
Should I add extra material for compaction?
Yes. Crushed stone compacts by about 10%, so add 10% to the calculated volume. For example, 9.26 yd³ becomes about 10.2 yd³. Sand compacts less, but adding 5% is safe.
What depth do I need for a walkway that only gets foot traffic?
For a paver walkway, use 4 inches of crushed stone base and 1 inch of sand. For a loose gravel walkway, 2–3 inches of gravel is enough. If you live in a cold climate with frost heave, go deeper—6 inches of base is safer.
How do I convert cubic yards to tons?
Multiply the cubic yards by the material’s density in tons per cubic yard. Crushed stone is about 1.4 tons/yd³, sand about 1.2 tons/yd³. Ask your supplier for the exact figure, as it varies with moisture and aggregate size.
Is it better to order bulk or bagged?
For anything more than about 1 cubic yard, bulk is cheaper and less labor-intensive. Bagged material is easier to transport and store, but you’ll pay several times more per volume. For a small 2×3 ft stepping stone path, bags are fine; for a full patio, go bulk.
Related
Formula used
in l | Lawn length | ft | 40 | 0 | 100000 in w | Lawn width | ft | 25 | 0 | 100000 in d | Depth | in | 3 | 0 | 120 out yd | Volume | yd³ | l * w * d / 324 | 2 out ft3 | Volume | ft³ | l * w * d / 12 | 1
Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.
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