Work out how much mulch, gravel, compost or topsoil you need — in cubic yards, cubic meters, bags, tons and dollars.
Diameter across the circle at its widest point.
Custom sizes OK — a typical 1.5 cu ft bag of potting soil or 0.5 cu ft gravel bag works too.
~1.4 t/yd³ covers most decorative gravel; use 1.5–1.6 for dense crushed stone.
Most beds do well with 2–3 inches. Use 2 inches to refresh an existing layer, 3 inches for new beds and weed suppression, and 1 inch for a fine topdressing. Keep mulch a few inches away from tree trunks and never deeper than 4 inches — overly deep mulch blocks oxygen from roots.
A cubic yard is 27 cubic feet, so it takes 13.5 two-cubic-foot bags or 9 three-cubic-foot bags. Bagged mulch suits small jobs, but bulk delivery by the yard becomes much cheaper once you need more than about 15–20 bags.
Yes. Organic mulches like shredded bark, wood chips and compost settle and decompose, losing roughly 20–30% of their depth within the first year. Adding about 1 inch — or 10–20% extra volume — compensates, or simply plan to top up each spring.
Yes. Gravel needs more depth than mulch to stay stable: at least 3 inches for decorative rock and 4 inches for paths or driveways that take traffic. Mulch at 2–3 inches is usually enough. Deeper gravel also suppresses weeds better and keeps rock from sinking into the soil.