How Much Mulch Do You Need?
Mulch volume = bed length × width × depth (in feet), then divide by 27 for cubic yards or by bag size for bag count. A 10 × 20 ft bed at the standard 3 inches needs 50 cubic feet — about 1.85 cubic yards bulk, or 25 of the 2 cu ft bags. Because mulch is sold in two completely different unit systems (bags at the store, cubic yards from the landscape supplier), the same bed can price out very differently depending on where you buy, which is why the calculator shows both.
Choosing the Right Depth
Depth is the decision that changes the total by 50% or more, and it depends on the job: 1–2 inches tops up an existing bed that just faded over winter; 2–3 inches is the standard for new planting beds — enough to block weeds and hold moisture without suffocating roots; 3–4 inchesis for serious weed suppression or bare areas around trees. Two rules almost everyone learns the hard way: never pile mulch against a trunk or stem (“mulch volcano” invites rot and rodents), and expect settled mulch to drop about a quarter in its first season, so a slightly generous first layer pays off.
Bags vs. Bulk: The Cost Crossover
Bagged mulch (2 or 3 cu ft) costs more per cubic foot but works for small beds and hatchback transport. Bulk mulch, delivered by the cubic yard (1 yard = 13.5 two-cuft bags = 9 three-cuft bags), wins once your project passes roughly 2–3 yards — often at half the per-foot price. The catch: bulk suppliers usually have a minimum delivery (often 3–5 yards) and a delivery fee, so measure accurately first. For the neighboring projects, our gravel calculator handles paths and driveways with the same math plus tonnage.
Frequently Asked Questions
How many bags of mulch are in a cubic yard?
One cubic yard equals 27 cubic feet, so it takes 13.5 of the standard 2 cu ft bags or 9 of the larger 3 cu ft bags. That is why bulk delivery wins on big jobs: a 5-yard order is roughly 68 two-cuft bags — a very different errand.
How much does mulch cost?
Bagged mulch typically runs $4–8 per 2 cu ft bag, which works out to $54–108 per cubic yard. Bulk mulch runs roughly $20–45 per yard plus a delivery fee (often with a 3–5 yard minimum). The crossover is usually around 2–3 yards: below that, bags and your own labor win; above it, bulk is dramatically cheaper per foot.
Can I put new mulch over old mulch?
Yes, as long as the total depth stays under about 4 inches and the old layer isn't matted, moldy, or full of weeds. Rake or fluff the old layer first so water penetrates, then top up 1–2 inches for color. If the old mulch has decomposed to something soil-like, you can work it into the bed instead of removing it.