Mulch Calculator
Estimate mulch volume and bag counts for a rectangular garden bed.
Enter positive dimensions. Changing measurement units converts your current measurements rather than resetting them.
Estimates are for rectangular areas. Check bag sizes and specifications with your supplier.
How to use this calculator
Mulch is sold by the bag or by the cubic yard. Measure your bed in feet and select the depth in inches.
Worked example
For a 12 ft × 8 ft bed with 3 inches of mulch, the volume is 24 cubic feet, or about 0.89 cubic yards. With 2-cubic-foot bags, you need 12 bags.
Example: a 12 × 8 ft flower bed
At 3 inches deep, a 12 × 8 ft bed needs 24 cubic feet of mulch, or about 0.89 cubic yards. That is 12 bags of 2 cubic feet each before any allowance for uneven ground.
Calculation method
Volume = length × width × depth, converted to matching units. One cubic yard is 27 cubic feet. Bags are rounded up to a whole bag.
Planning tip
Different mulch types settle differently. Avoid piling mulch directly against tree trunks or plant stems.
Frequently asked questions
Can I use metric measurements?
Yes. Select meters and centimeters from the measurement units menu. The results include cubic meters as well as US units.
Is this an exact purchase quantity?
No. It is a planning estimate. Irregular shapes, settling, compaction and supplier packaging can change the amount needed.
How much mulch do I need?
Choosing a mulch depth
A 2–3 inch layer is a common starting point for many landscape beds. The appropriate depth depends on the mulch, plants, existing soil and local conditions. Measure the depth you actually plan to install rather than assuming every bed needs the same amount.
Buying bags or bulk mulch
For small areas, bagged mulch may be easier to transport. For larger areas, ask suppliers for a bulk cubic-yard quote. Compare the total delivered cost, not just the price per bag. The calculator counts full bags and rounds up.
Handling beds with unusual shapes
Split an L-shaped or curved bed into smaller measurable sections. Calculate each section separately and add the volumes. Avoid including paths, patios or areas that will not receive mulch.
Example: two separate beds
Bed A: 12 × 8 ft at 3 inches requires 24 ft³. Bed B: 6 × 4 ft at 3 inches requires 6 ft³. Together they require 30 ft³, about 1.11 yd³, or 15 bags of 2 ft³ each.
Common mistakes
Keep length and width in the same units, convert depth from inches to feet, and check whether the package is labeled in cubic feet rather than weight. Do not cover plant crowns or pile mulch against trunks.
Explore the other free tools: Mulch calculator, Gravel calculator, and Raised bed soil calculator.