Mulch Calculator
Work out how many bags or cubic yards of mulch you need for any garden bed or landscaped area.
The mulch calculator works out how much mulch you need for any garden bed or landscaped area. Enter the bed dimensions and your target depth - 3 inches is the sweet spot for moisture retention and weed suppression without smothering plants. The calculator returns cubic yards (the unit bulk mulch is sold in) and the bag count for standard 2 cubic foot bags. Common questions like "how many bags of mulch for 100 sq ft" or "how much mulch do I need for a 20x5 bed" can be answered in seconds.
Explore all our landscaping materials calculator tools, or browse the full construction & home improvement diy calculators.
Frequently asked questions
At the recommended 3 inch depth, 100 sq ft needs 25 cubic feet of mulch. That is 13 bags of standard 2 cubic foot mulch, or about 0.93 cubic yards if buying in bulk. Two inches of depth would take 17 cubic feet (9 bags) and 4 inches would take 33 cubic feet (17 bags).
3 inches is ideal for most landscape beds - enough to suppress weeds and retain moisture without smothering plant crowns. Use 2 inches for annual top-ups over existing mulch and 4-6 inches for new beds or areas needing aggressive weed suppression. Keep mulch a few inches away from tree trunks.
Yes - bulk mulch delivered is typically 30-50% cheaper per cubic yard than buying bags. Break-even is usually around 5-10 bags. If you need more than 1 cubic yard (about 13 standard bags), bulk is almost always the better deal. Many nurseries deliver for a flat fee.
One cubic yard equals 27 cubic feet. With standard 2 cubic foot bags, that is 14 bags (27/2 = 13.5, rounded up). One cubic yard covers about 108 sq ft at 3 inches deep, or 162 sq ft at 2 inches deep.
Yes - the volume calculation is identical for any spread material: mulch, topsoil, compost, gravel or sand. Just enter your bed size and depth. Bag sizes vary by material though - topsoil is often sold in 0.75 or 1 cubic foot bags, gravel in 0.5 cubic foot bags. Adjust the bag size input to match what your supplier sells.