Rectangular bed
Square feet = length × width. Cubic feet = square feet × depth in inches ÷ 12.
Mulch calculator / How much mulch do I need?
Quantity guide
How Much Mulch Do I Need?
US: square feet × added inches ÷ 12 = cubic feet. Metric: square metres × added centimetres ÷ 100 = cubic metres. Multiply cubic metres by 1,000 for litres. Divide volume by your package's printed volume in matching units, then round up to whole bags.
Example: a 12 × 8 ft bed with 3 new inches needs 24 ft³ — about 0.889 yd³ or twelve 2 ft³ bags, before any allowance.
Count only the ground receiving mulch and the new layer you will add, not the finished depth over existing mulch.
Subtract the ground you will leave uncovered
Use this worksheet for one rectangular bed. Subtract only measured patches you plan to leave bare. If you will mulch beneath plants, keep that ground in the area; no generic planted-area percentage is assumed. Measurements stay in your browser.
Your measured order
Area receiving mulch— sq ft
New volume— cu ft
Bulk equivalent— cu yd
Whole bags—
Enter your measurements. No depth, bag size or extra allowance is assumed.
Check the area ledger
Whole bed—Uncovered total—Net mulched area—
- List an uncovered piece to see what is deducted.
Calculation and limits
Net area = bed length × width − total uncovered area. For each group, multiply one piece’s area by its count; a rectangle uses length × width and a circle uses π × (diameter ÷ 2)². Enter other shapes as a measured square-foot area. Cubic feet = net area × added depth in inches ÷ 12; cubic yards = cubic feet ÷ 27. Whole bags round up once from cubic feet ÷ your entered package volume.
This worksheet accepts up to 12 uncovered-piece groups, each with a whole-number count from 1 to 10,000. It multiplies each entered footprint by its count, then subtracts the total from the bed area. It cannot check piece positions or detect overlap, so grouped footprints must not overlap or extend beyond the bed. No waste or settling allowance is added; the surplus shown comes only from whole-bag rounding. For irregular outer beds, measure the net footprint in sections and enter it as a Known area in the main mulch calculator.
The Iowa State University Extension area-and-depth method explains area-and-depth volume calculations. Metric and U.S. unit factors follow the NIST conversion tables. Subtracting only the pieces that stay uncovered is ordinary area arithmetic, not a material-performance guarantee.
The calculation
Mulch quantity formula
Round bed
Square feet = π × (diameter ÷ 2)². Then multiply by depth in inches ÷ 12.
Bulk mulch
Cubic yards = cubic feet ÷ 27. Keep the unrounded volume visible when asking a supplier for a quote.
Bagged mulch
Bags = cubic feet ÷ the bag size printed on the package. Round up to a whole bag.
Worked measurements
Two examples you can check
| Bed | Area | Volume | 2 ft³ bags |
|---|---|---|---|
| 12 × 8 ft rectangle | 96 ft² | 24 ft³ / 0.889 yd³ | 12 |
| 10 ft diameter circle | 78.54 ft² | 19.63 ft³ / 0.727 yd³ | 10 |
The examples use the displayed formulas: volume is area × 3 ÷ 12, cubic yards are cubic feet ÷ 27, and bags are rounded up from cubic feet ÷ 2. Calculations use the unrounded circle area; displayed decimals are rounded only at the end. See the Iowa State University Extension area-and-depth method.
More than one bed
Add areas without hiding the math
Calculate every bed with its own shape, dimensions, and depth. Add the cubic-foot results for the project total, then convert that total to cubic yards or bags. Keeping areas separate makes it easier to check a narrow border, a circular bed, or a section with a different depth.
Use the multiple-bed mulch calculator guide for a worked two-area example, then open the mulch project planner when you also need an order summary and installation checklist.
Common questions
How much mulch do I need FAQ
How deep should I calculate?
Use the additional depth you intend to spread. If usable mulch is already present, measure it first and use the mulch depth and top-up calculator to subtract that settled layer from your chosen finished depth.
Do I round cubic yards?
Keep the calculated decimal for comparison and ask the supplier how partial-yard orders are handled. Bag counts are rounded up because a project needs whole bags.
What if my bed is not a rectangle or circle?
Split an irregular bed into smaller rectangles or circles, calculate each part, and add the volumes. This is the same multi-area method used by the calculator.
How much mulch is in a bag of mulch?
The volume is the number printed on the bag, not a universal weight. CoverCalc Pro accepts common 1.5, 2 and 3 cubic-foot bags plus 40, 42.5, 50 and 60 liter options; use your label for the final quantity.
How much coverage does one bag of mulch provide?
Coverage depends on bag volume and depth. A 2-cubic-foot bag covers about 12 square feet at 2 inches deep, 8 square feet at 3 inches, or 6 square feet at 4 inches before any project allowance.
How many bags of mulch do I need for 200 square feet?
At 3 inches deep, 200 square feet needs 50 cubic feet. With 2-cubic-foot bags, that is 25 whole bags before any allowance; change the depth and bag size for your project.
How many bags of mulch do I need for 300 square feet?
At 3 inches deep, 300 square feet needs 75 cubic feet. With 2-cubic-foot bags, that is 38 whole bags after rounding up, before any allowance; change the depth and bag size for your project.
How many pounds is 2 cubic feet of mulch?
Volume alone cannot determine pounds because material density and moisture vary. Use the supplier's weight-per-cubic-yard value when you need a weight estimate; the main calculator keeps weight optional for that reason.
How much mulch do I need for my garden?
Measure each garden bed, choose the added depth, calculate each area in square feet or square metres, and add the volumes. The free mulch calculator keeps each bed separate and converts the total to cubic yards, cubic metres or whole bags.
Can I use a mulch calculator with square feet?
Yes. Enter square-foot dimensions for each rectangle, circle or known area, then enter the depth in inches. The calculator converts square feet × depth into cubic feet, cubic yards and whole bags.
How do I calculate cubic yards for mulch?
Multiply square feet by the added depth in inches, divide by 12 to get cubic feet, then divide by 27 to get cubic yards. For example, 100 square feet at 3 inches is 25 cubic feet, or about 0.926 cubic yards.
Should I count a paved path inside the bed?
Leave it out if it will stay uncovered. Measure its footprint and subtract it from the surrounding bed area before applying the added depth. Do not deduct the same overlapping ground twice.
Should I subtract plants from a mulch bed?
Only subtract a measured patch if you plan to leave that ground bare. A plant canopy does not by itself mean the ground should be excluded; if you will mulch beneath it, keep that ground in the bed area. This worksheet does not apply a generic planted-area percentage.
Can I enter metric measurements in the net-area worksheet?
Yes. Choose Metric, then enter lengths in metres, known areas in square metres, depth in centimetres and bag volume in litres. The worksheet shows area in square metres, volume in litres and cubic metres, and whole bags rounded up. Unit changes convert your entries without sending or saving them.
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