Mulch Calculator
Free mulch calculator. Compute cubic yards or 2-cubic-foot bags needed for any garden bed or landscape area — from length, width, and depth in inches.
Quick answer
Cubic yards of mulch = (length × width × depth) ÷ 27, where depth is in feet. A standard 2-cubic-foot bag covers ~12 sqft at 2-inch depth. Bulk delivery is much cheaper than bagged for any project over 3-4 cubic yards.
Mulch / Gravel Calculator
How it works
Calculates how much mulch you need in cubic yards (for bulk delivery) or 2-cubic-foot bags (for store pickup). Volume = area × depth, with depth typically 2–4 inches for most flower beds.
When to use it
Use this every spring and fall when refreshing landscape beds. Bulk delivery is much cheaper per cubic yard than bagged mulch but requires a place to dump it. Bagged mulch wins for small jobs and apartment dwellers.
Common mistakes
Spreading mulch too thick (over 4 inches) — it suffocates roots, holds moisture against trunks, and encourages pests. Also piling mulch against tree trunks (the 'mulch volcano') causes bark rot and tree decline.
How the mulch calculator works
Volume = length × width × depth. Convert depth from inches to feet (divide by 12). Divide cubic feet by 27 to get cubic yards (the standard unit for bulk landscaping material). For bagged mulch, divide cubic feet by 2 to get the number of standard 2-cubic-foot bags. The calculator outputs both so you can compare costs — bagged is typically 2-3× the per-yard cost of bulk.
When to use it
Refreshing landscape beds in spring (most beds need 1-3 inches of fresh mulch annually). Estimating cost before calling a bulk supplier. Sizing a one-time order for a new garden bed installation. Computing how many bags fit in your car for a DIY trip. Planning playground or pathway mulch installations (deeper applications, 4-12 inches, for impact attenuation or weed suppression).
Common mistakes
- Mulching too deep. 2-3 inches is the sweet spot for landscape beds. More than 4 inches causes 'mulch volcanoes' that suffocate roots, attract pests, and rot trunks. Refresh thin existing mulch, don't pile new on top.
- Bagged when bulk is cheaper. 3+ cubic yards is almost always cheaper as bulk delivery. The breakeven is usually 50-70 bags, depending on local prices.
- Forgetting that mulch settles. Fresh mulch settles 25-30% in the first 6 months. The 3-inch layer you applied is a 2-inch layer by season's end. Plan slightly higher than your target depth.
Frequently asked questions
How many cubic yards of mulch do I need?
Multiply bed length × width × depth (all in feet), then divide by 27. The calculator handles depth-in-inches automatically. A 100 sqft bed at 3-inch depth needs about 0.93 cubic yards.
How many bags of mulch in a yard?
13.5 bags of standard 2-cubic-foot mulch per cubic yard (since 1 cubic yard = 27 cubic feet). Bagged mulch typically costs 2-3× as much per cubic yard as bulk delivery — bulk wins for orders over about 3 yards.
How deep should mulch be?
2-3 inches for most landscape beds. 4-6 inches for new beds with bare soil. Don't go deeper than 4 inches around tree trunks — 'volcano' mulching damages bark and invites pests. Refresh annually rather than piling on top.