How this gravel calculator works
Estimating loose material such as gravel, sand, topsoil or mulch comes down to one idea: volume = area × depth. First work out the area you are covering, then multiply by how deep you want the layer to sit. The result is a volume, which suppliers usually quote in cubic yards (US) or cubic meters (metric), and which bagged products quote in cubic feet.
For a rectangle, area is length × width. For a circle, area is π × radius², where the radius is half the diameter. The key is keeping units consistent: this tool converts your depth into the same unit as the area before multiplying, so a depth entered in inches is turned into feet first, and a depth in centimeters is turned into meters.
Once it has the volume, the calculator converts between cubic feet, cubic yards and cubic meters (1 cubic yard = 27 cubic feet). It then multiplies the volume by an approximate density for the material you choose to estimate weight, and divides the cubic-foot figure by 0.5 to estimate how many half-cubic-foot bags you would need, rounding up.
Reference note: densities used here are commonly cited averages — gravel ≈ 1.5 t/yd³ (≈ 1.68 t/m³), sand ≈ 1.35 t/yd³, topsoil ≈ 1.1 t/yd³, mulch ≈ 0.4 t/yd³, crushed stone ≈ 1.6 t/yd³. Real weight varies with moisture, compaction and stone size, so treat tonnage and bag counts as estimates and order around 5–10% extra.
Frequently asked questions
- How much gravel do I need?
- Multiply the area you are covering by the depth of material to get the volume. For a rectangle, area is length × width; for a circle it is π × radius². Keep the units consistent, then read the result in cubic yards or cubic feet — this calculator does the conversions and adds an approximate weight.
- How deep should gravel be?
- A decorative gravel topping is often about 2 inches (5 cm) deep, while a driveway or path that carries traffic is commonly 4 inches (10 cm) or more, sometimes laid in layers over a compacted base. Deeper layers use more material, so check the depth recommended for your project.
- How many cubic yards are in a ton of gravel?
- It depends on density. Typical gravel weighs roughly 1.4–1.5 US tons per cubic yard, so one ton is about 0.65–0.7 cubic yards. Lighter materials such as sand, topsoil and mulch give more volume per ton. These figures are approximate because moisture and stone size change the real weight.
- Rectangle or circle — which area formula should I use?
- Use the rectangle option for square or rectangular beds, paths and driveways, entering length and width. Use the circle option for round features such as fire-pit surrounds or planters, entering the diameter. The tool applies the right formula once you pick a shape.
- Does the material type change the weight?
- Yes. Volume stays the same for a given area and depth, but weight depends on density. Crushed stone and gravel are heavy at roughly 1.5–1.6 tons per cubic yard, while mulch is very light at around 0.4 tons per cubic yard. Selecting the material applies its approximate density to the weight estimate.
- Is this gravel calculator accurate?
- The volume math is exact for the shape and depth you enter. The weight and bag figures are estimates based on commonly cited average densities and vary with moisture, compaction and stone size. Order around 5–10% extra for settling and uneven ground, and confirm quantities with your supplier.