Estimates for planning only. Always confirm measurements and order a little extra for waste and cuts.
How the mulch calculator works
Mulch is sold by the cubic yard in bulk or in 2-cubic-foot bags. This calculator converts your bed area and desired depth into both, so you order enough without a pile left over.
The formula
Volume is area times depth, with depth converted from inches to feet:
Cubic feet = area × (depth ÷ 12)
Cubic yards = cubic feet ÷ 27 · Bags = cubic feet ÷ 2
How deep should mulch be?
Two to three inches is the sweet spot for most beds: deep enough to suppress weeds and hold moisture, not so deep that it smothers roots. Use about 2 inches for annual top-ups over existing mulch, and 3 inches for a fresh bed. Keep mulch a couple inches away from trunks and stems to prevent rot.
Pro tips
- One cubic yard covers about 100 square feet at 3 inches deep.
- Bulk mulch by the yard is much cheaper than bags once you need more than ~10 bags.
- Refresh color and depth annually rather than piling on a thick new layer every year.
- Don't mound mulch against trunks, the dreaded 'mulch volcano' rots bark.
Frequently asked questions
How many bags of mulch are in a cubic yard?
About 13.5 bags, since most bags hold 2 cubic feet and a cubic yard is 27 cubic feet.
How much mulch do I need for 100 square feet?
Roughly 0.6 cubic yards at 2 inches deep, or about 0.93 cubic yards at 3 inches deep.
Is bulk or bagged mulch better?
Bagged is convenient for small beds and easy to carry. Bulk by the yard is cheaper and less plastic once you need a lot, but you'll need a truck or delivery.
How deep should I lay mulch?
Two to three inches. Less than that won't suppress weeds; much more can suffocate roots and hold too much moisture against stems.
Will I have leftover mulch?
A little extra is handy for touch-ups. This tool rounds bags up, so expect to have a partial bag or a small bulk remainder.
