Mulch Calculator
Enter your garden bed's dimensions — the cubic yards and bag count update as you type, and the link in your address bar always reflects your numbers.
How this calculator works
We start with the bed's surface area (length × width), then convert your chosen depth from inches to feet and multiply to get volume in cubic feet. Dividing by 27 (the number of cubic feet in a cubic yard) gives the bulk-order quantity landscape suppliers price by. For bagged mulch, we divide the cubic-foot volume by 2, since 2 cu ft is the most common retail bag size, and round up — you can't buy a fraction of a bag.
Worked example
A bed 20 ft long and 5 ft wide, mulched 3 inches deep: the area is 100 sq ft, and 3 inches is 0.25 ft, so the volume is 100 × 0.25 = 25 cubic feet. Divided by 27, that's about 0.93 cubic yards — worth rounding up to 1 cubic yard if you're ordering bulk. In 2-cubic-foot bags, 25 ÷ 2 rounds up to 13 bags.
Frequently asked questions
How deep should my mulch layer be?
2 to 3 inches is typical guidance for most garden beds — enough to suppress weeds and hold soil moisture without smothering roots. Around trees, up to 4 inches is sometimes used, but keep it pulled back from the trunk itself; piling mulch against the bark (a "mulch volcano") traps moisture against the trunk and invites rot and pests.
Is buying mulch in bulk cheaper than bags?
Generally, yes, once you get past a certain volume — bagged mulch carries a packaging and handling premium per cubic foot. The crossover where bulk (delivered by the cubic yard) starts winning on price is usually somewhere around 2 to 3 cubic yards, though exact pricing varies a lot by supplier and location, so it's worth comparing both for your specific quantity.
Does the type of mulch change the calculation?
No — this calculator is purely volume-based, so it applies the same whether you're using shredded bark, wood chips, pine straw, or rubber mulch. What does change by material is weight per bag and sometimes bag size at different retailers, so double-check the cubic-foot volume printed on your specific bag.
How often should I re-mulch a bed?
Most organic mulches break down over time and are commonly topped up annually or every two years, depending on the material and climate — finer mulches like shredded bark decompose faster than coarser wood chips. A quick visual check (has the layer thinned below 2 inches?) is a simpler guide than a fixed calendar.