A common mix is 60% topsoil, 30% compost and 10% potting mix or other amendments.
How to calculate mulch, soil and gravel
Every landscaping material is sold by volume, so the calculation is always area × depth. Measure each bed or path and work out its area: length × width for rectangles, π × radius² for circles such as tree rings, and half the base × height for triangles. Odd shapes can be split into these pieces, or you can enter a known area. Multiply by the depth, converting inches to feet, to get cubic feet, and divide by 27 to get cubic yards, the usual unit for bulk delivery in North America. MulchCalc does all of this for every bed you add and converts the total into cubic metres, bags and approximate weight.
Recommended depths
Mulch works best at 2–4 inches: enough to block light from weed seeds and hold moisture, without smothering roots. Keep it a few inches clear of plant stems and tree trunks. Decorative gravel paths need about 2–3 inches over landscape fabric, while gravel driveways need 4–6 inches of crushed stone on a compacted base. New lawns need 4–6 inches of topsoil, and new vegetable beds benefit from 2–3 inches of compost dug in. Raised beds are usually filled to their full height of 8–24 inches with a blend of topsoil and compost.
Bags, yards and tons
A cubic yard is 27 cubic feet, so it equals about 13.5 bags of 2 cubic feet or 18 bags of 1.5 cubic feet. In metric countries, bags are sold in litres; 50 litres is about 1.77 cubic feet. Heavy materials such as gravel, sand and topsoil are often sold by the ton or tonne. The weights here are typical values for dry material: crushed stone about 1.4 tons per cubic yard, sand 1.35, topsoil 1.1 and wood mulch around 0.3. Wet loads weigh more, so check with your supplier, and make sure a trailer or pickup can carry the weight before collecting it yourself.
Ordering tips
Order around 5–10% extra to allow for settling, uneven ground and spillage. For jobs over two or three cubic yards, bulk delivery is usually cheaper than bags, even with a delivery charge, but you will need a place to tip the load and a wheelbarrow to move it. Your beds and prices are saved only in this browser.
Frequently asked questions
How deep should a raised bed be?
8–12 inches for most vegetables, 18–24 for root crops or poor ground.
Can I fill the bottom with logs?
Yes. Hügelkultur-style filling with logs and branches reduces soil needed.
Will it settle?
Yes. Top up with compost after the first season.
Is MulchCalc free?
Yes, with no sign-up or ads.
Are my beds saved?
Yes, in this browser only.