Mulch Calculator

How this calculation works

Cubic yards needed = (bed area in sq ft x depth in inches / 12) / 27 — remember a cubic yard is 27 cubic feet (a cube 3ft x 3ft x 3ft), the same conversion used across every bulk landscaping material on this site (see cubic yards explained). A standard 2 cu ft bag covers roughly 8 sq ft at a 3-inch depth or 12 sq ft at a 2-inch depth.

The bag-vs-bulk crossover: bulk mulch typically runs a fraction of the per-cubic-foot cost of bagged mulch once you account for bag pricing, but bulk usually requires a delivery minimum (often around 2-3 cubic yards) and somewhere to dump a pile. For small beds under roughly 1-2 cubic yards, bags are usually the more practical and often cheaper total option once delivery fees are factored in; above that, bulk wins clearly.

Common mistakes

• Applying the same depth to every mulch type — shredded bark settles and compacts faster than nuggets, so what starts as a 3-inch layer can thin to under 2 inches within a season.
• Buying bagged mulch for a large bed without checking the bulk-yard price, which is often dramatically cheaper per cubic foot once bed size crosses a couple cubic yards.
• Not accounting for existing mulch depth — topping off an established bed needs less new material than starting from bare soil.
• Piling mulch against tree trunks or stems ('mulch volcanoes'), which traps moisture against bark and promotes rot regardless of how well the quantity was calculated.
• Ordering bulk mulch without confirming the supplier's cubic-yard measurement is a compacted or loose measure — a 'heaping' scoop can measure differently between suppliers, so a delivered pile can look smaller than the ordered yardage if it settles in transit.
• Applying fresh mulch right up against siding or a wood structure's base, which holds moisture against the material in a way that promotes rot or pest issues over time.

Shopping summary

For beds under roughly 1-2 cubic yards, buy bagged mulch by the 2 cu ft bag, rounded up from total cubic feet needed; for larger beds, order bulk by the cubic yard from a landscape supplier, rounding up to the nearest half-yard and checking their delivery minimum.

Worked example: a 150 sq ft bed at 3 inches depth needs (150 x 3/12)/27 ≈ 1.39 cubic yards, or about 37.5 cubic feet. At 2 cu ft per bag, that's about 19 bags — right around the point where bulk delivery (if the supplier's minimum is 1-2 yards) starts to beat bagged pricing, so it's worth pricing both options at exactly this size rather than defaulting to bags out of habit.

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