FitAndFillMulch Calculator: Cubic Yards and Bags
Estimate mulch for a rectangular or round bed in cubic yards and bags, and compare the cost of bulk delivery with bagged mulch.
How the calculation works
area (sq ft) = length × width or π × (diameter ÷ 2)² volume (ft³) = area × depth (in) ÷ 12 cubic yards = volume (ft³) ÷ 27 bags = volume with extra ÷ bag size (ft³), rounded up A shortcut: square feet × depth in inches ÷ 324 gives cubic yards, because 27 × 12 = 324.
Worked example
A 10 ft × 10 ft bed is 100 sq ft. At 3 inches deep it needs 100 × 3 ÷ 12 = 25 ft³, or 0.93 yd³.
In 2 ft³ bags that is 12.5 bags, so 13 bags. With 10 % extra it is 14 bags. One cubic yard equals 13.5 two-cubic-foot bags and covers 108 sq ft at 3 inches deep.
Assumptions and limits
- The bed is a rectangle or a circle with an even depth.
- Bag size is the volume printed on the bag; common sizes are 1, 1.5, 2 and 3 cubic feet but they vary by brand.
- Mulch settles and breaks down, so you may need a little more at the start and a top-up later.
- Prices are only what you type in; the tool does not look up local prices.
Frequently asked questions
How deep should mulch be?
For most garden beds a layer of about 2 to 4 inches is typical. Go thinner with fine mulch and thicker only where weeds are a problem. Keep mulch a few inches away from tree trunks and plant stems rather than piling it against them.
How far does one cubic yard go?
About 162 sq ft at 2 inches deep, 108 sq ft at 3 inches and 81 sq ft at 4 inches. The calculator shows the coverage for the depth you enter.
Is bulk mulch cheaper than bags?
Bulk is often cheaper per cubic foot for larger areas, but delivery fees, minimum orders and rounding can change that. Enter your local prices in the optional fields to compare for your own job.
Why is there a half-yard line?
Some suppliers sell and deliver in half-yard steps. The tool shows your total rounded up to the next half yard so you can ask for the right amount.
Will I need to add mulch later?
Mulch settles and breaks down over time, so many gardeners top up each year or two. The extra percentage helps cover settling during the first fill.
Sources
- Unit definition: 1 cubic yard = 27 cubic feet
- Bag volume: entered by the user from the label of the product they plan to buy (the tool does not assume a brand)
Guides that help
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