Mulch Calculator - Bags & Cubic Yards Needed

  • 2 cu ft bag
  • 3 cu ft bag
Results
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Work out how much mulch your garden beds need with our Mulch Calculator. Enter the bed length and width plus your target depth in inches, and get the volume in cubic feet and cubic yards along with the number of bags (2 or 3 cu ft sizes).

Depth is the key variable: 2-3 inches suppresses weeds and holds moisture without suffocating roots, while more than 4 inches can shed water and starve plants of air. Keep mulch a few inches away from trunks and stems to prevent rot.

For large beds, bulk mulch sold by the cubic yard is far cheaper than bags — the calculator shows both so you can compare. One cubic yard equals about nine 3-cu-ft bags. Refresh mulch yearly for appearance and weed control, topping up rather than replacing unless the old layer is matted or over-deep.

Formula
cu ft = L × W × D(in) ÷ 12 | bags = ceil(cu ft ÷ bag size) | cu yd = cu ft ÷ 27

FAQ

How much mulch do I need?
Multiply bed length × width × depth (converted to feet) for cubic feet, then divide by the bag size for bag count. A 100 sq ft bed at 3 inches deep needs about 25 cu ft — nine 3-cu-ft bags.
How deep should mulch be?
2-3 inches is ideal for most beds: deep enough to suppress weeds and retain moisture, but not so deep that it suffocates roots. Keep mulch away from tree trunks and plant stems.
How many bags of mulch in a cubic yard?
One cubic yard (27 cu ft) equals about nine 3-cu-ft bags or 13.5 two-cu-ft bags. Bulk delivery by the yard is much cheaper for large areas.
Should I remove old mulch first?
If the existing layer is under 2 inches, top it up directly. If it is over 3 inches or matted, rake some off first — too much mulch prevents water and air from reaching roots.

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