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Compost mulch chart
Put your bed area, compost mulch depth and waste allowance in: 1200 sq ft at 3 inches with 10% waste needs 1,320.00 sq ft, 12.22 cubic yards exact — order 13 cubic yards.
★ CONSTRUCTION · MULCH · COMPOST MULCH CHART
Compost Mulch Chart: 1200 Sq Ft, 3 Inches, Order 13 Yards
On the defaults — a 1200 square foot bed at 3 inches deep with a 10% waste allowance — you need 1,320.00 square feet of cover, 12.22 cubic yards exact, so order 13 cubic yards. This is the COMPOST version — the mulch chart for compost, which settles more than bark — the pecan-mulch-chart page is the PECAN version, the palm-mulch-chart page is the PALM version, and the mulch-chart page is the GENERAL version for any loose mulch.
What does 12.22 cubic yards of compost mulch mean?
It means a 1200 square foot bed, once the 10% waste allowance is added, needs 1,320.00 square feet of cover at 3 inches deep — 330.00 cubic feet, which is 12.22 cubic yards. Because mulch is sold by the whole yard, you order 13 cubic yards: the extra 0.78 yard covers settling and the thin spots every bed has. At 3 inches, one cubic yard covers 108.0 square feet, so the same bed at 2 inches would need only 8.15 yards, and at 4 inches it would need 16.30 yards.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Area needed | area × (1 + waste ÷ 100) | 1,320.00 sq ft — 1200 × 1.10. |
| Exact volume | area needed × depth ÷ 324 | 12.22 cubic yards — 1,320.00 × 3 ÷ 324. |
| Order quantity | round exact volume up to a whole yard | 13 cubic yards — the next whole yard above 12.22. |
| Coverage per yard | 324 ÷ depth | 108.0 sq ft per yard — 324 ÷ 3. |
| Area behind a target volume | target volume × 324 ÷ depth ÷ (1 + waste ÷ 100) | 1200 sq ft — 12.22 × 324 ÷ 3 ÷ 1.10, rounded. |
| Depth behind a target volume | area needed × depth ÷ 324, solved for depth | 3 inches — the depth that turns 1,320.00 sq ft into 12.22 yards. |
| Waste behind a target volume | target volume × 324 ÷ depth ÷ area − 1, as a percent | 10% — the allowance that turns 1200 sq ft into 1,320.00 sq ft. |
Three things to check before you trust the number
First, measure the bed honestly: length times width for each bed, added together, with L-shaped beds split into rectangles. A guessed area moves the order by the same percentage as the guess. Second, keep the depth honest: compost settles and compacts more than bark, so a layer spread at 3 inches may sit closer to 2 inches within weeks — if you want 3 inches after settling, spread a little deeper and say so. Third, do not skip the waste allowance on compost: it spills off wheelbarrows, washes in rain and settles into dips, so the 10% allowance is the difference between finishing the bed and running short with the truck already gone.
Worked example
Area 1200 sq ft, depth 3 inches, waste 10%. Area needed: 1200 × 1.10 = 1,320.00 sq ft. Exact volume: 1,320.00 × 3 ÷ 324 = 12.22 cubic yards. Order: round 12.22 up to 13 cubic yards. Drop the waste to 0% and the exact volume falls to 11.11 yards, order 12; drop the depth to 2 inches and it falls to 8.15 yards, order 9. Depth moves the answer faster than waste does, because every inch adds a full layer across the whole bed.
Compost mulch lookup table
Every row below applies 10% waste to the area first, then divides by 324: yards = area needed × depth ÷ 324, rounded up to the next whole yard for the order. Find your bed size and depth, read across, and order the last column.
| Area (sq ft) | Depth (inches) | Area needed (sq ft, 10% waste) | Exact (cubic yards) | Order |
|---|---|---|---|---|
| 250 | 2 | 275.00 | 1.70 | 2 cubic yards |
| 250 | 3 | 275.00 | 2.55 | 3 cubic yards |
| 500 | 2 | 550.00 | 3.40 | 4 cubic yards |
| 500 | 3 | 550.00 | 5.09 | 6 cubic yards |
| 750 | 2 | 825.00 | 5.09 | 6 cubic yards |
| 750 | 3 | 825.00 | 7.64 | 8 cubic yards |
| 1000 | 2 | 1,100.00 | 6.79 | 7 cubic yards |
| 1000 | 3 | 1,100.00 | 10.19 | 11 cubic yards |
| 1200 | 3 | 1,320.00 | 12.22 | 13 cubic yards |
| 1250 | 3 | 1,375.00 | 12.73 | 13 cubic yards |
| 1500 | 2 | 1,650.00 | 10.19 | 11 cubic yards |
| 1500 | 4 | 1,650.00 | 20.37 | 21 cubic yards |
| 1750 | 3 | 1,925.00 | 17.82 | 18 cubic yards |
| 2000 | 3 | 2,200.00 | 20.37 | 21 cubic yards |
| 2500 | 2 | 2,750.00 | 16.98 | 17 cubic yards |
| 3000 | 3 | 3,300.00 | 30.56 | 31 cubic yards |
Every branch, checked
A 1200 square foot bed at 3-inch depth with 0% waste gives 11.11 cubic yards exact, order 12 cubic yards. The same bed at 2-inch depth with 10% waste gives 8.15 cubic yards exact, order 9 cubic yards. A 1100 square foot bed at 3-inch depth with 10% waste gives 11.20 cubic yards exact, order 12 cubic yards. A 1300 square foot bed at 3-inch depth with 10% waste gives 13.24 cubic yards exact, order 14 cubic yards. Each branch changes exactly one input, so the difference from 12.22 isolates that input.
The reverses, worked backwards
The area behind 12.22 cubic yards is 1200 sq ft: at 1100 sq ft the figures are 11.20 cubic yards exact, order 12 cubic yards, and at 1300 sq ft they are 13.24 cubic yards exact, order 14 cubic yards. The depth behind 12.22 cubic yards is 3 inches: at 2 inches the figures are 8.15 cubic yards exact, order 9 cubic yards, and at 4 inches they are 16.30 cubic yards exact, order 17 cubic yards — one inch either way moves the order by about 4 to 5 yards. The waste behind 12.22 cubic yards is 10%: at 5% the figures are 11.67 cubic yards exact, order 12 cubic yards, and at 15% they are 12.78 cubic yards exact, order 13 cubic yards — waste moves the exact volume but not always the order.
What the defaults assume
The defaults assume a flat 1200 square foot bed, a uniform 3-inch layer, and a 10% waste allowance. Real compost beds are rarely flat: slopes shed mulch downhill, paths and tree trunks eat into the area, and compost compacts under rain, so measure the planted area only and keep the waste allowance on sloped ground. Zero square feet is the honest edge: 0.00 cubic yards exact, order 0. A depth of zero or below, a negative area, or a negative waste allowance is rejected, because none of them describes a real bed.
Who uses this
A gardener mulching a large vegetable bed with compost: the 1200 square foot headline is a big kitchen-garden bed, and the table covers everything from a 250 square foot border to a 3000 square foot orchard floor. A landscaper quoting a compost job: the waste column protects the quote, and the order column is the number given to the supplier. A homesteader spreading bulk compost on paths: the 2-inch rows are the path depths, and the 3-inch rows are the bed depths. A community garden coordinator splitting a bulk delivery: each plot reads its own row, and the orders add up to the truckload.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is in the inputs. A guessed area, a depth measured before settling, or a skipped waste allowance will each move the answer by exactly the amount of the error, every load. The model does not include compost nitrogen drawdown in soil, compaction over the season, or delivery minimums — a supplier may sell only in whole yards or charge extra below a minimum, so confirm the order quantity with the supplier. This page is a calculation tool, not landscaping advice.
Cite this calculator
Compost mulch 1200 sq ft at 3-inch depth with 10% waste needs 1,320.00 sq ft, 12.22 cubic yards exact, order 13 yards. Calculator, plus 16-row lookup table. Source: Bright Side Kit, https://brightoolbox.com/compost-mulch-chart/, accessed 30 October 2026 (2026-10-30).
Frequently asked questions
Why does the table apply waste to the area first?
Because waste is lost cover: spillage, wind and uneven ground mean you need more covered area than the bed measures. Adding 10% to the area, then converting to yards, keeps the waste in the same units as the bed. Applying it after the conversion gives the same number here, but the area-first order keeps the table readable.
How deep should compost mulch really be?
Three inches is the standard bed layer on this page, and 2 inches suits paths and top-ups. Compost compacts more than bark, so a 3-inch spread may settle toward 2 inches; if you want a lasting 3-inch layer, spread slightly deeper and expect to top up during the season.
Does compost mulch feed the soil?
Finished compost adds nutrients rather than drawing them away: it feeds soil life and improves structure as it continues to break down. Very fresh, woody material can temporarily tie up nitrogen, which is why this chart assumes finished compost; this calculator prices volume only and does not judge the gardening choice.
What if my bed is not a rectangle?
Split it into rectangles, measure each, and add the areas before entering the total. A circle uses radius times radius times 3.14. Guessing one number for an irregular bed is the most common reason orders come up short.
Why order 13 yards when the exact figure is 12.22?
Because mulch is sold by the whole yard and you cannot buy 0.22 of a yard from most suppliers. Rounding up also covers settling and thin spots; the 0.78 yard of headroom is cheaper than a second delivery for a shortfall.
Can I use this chart for other mulch types?
The volume math is the same for any loose mulch — area, depth and waste convert the same way — but settling and coverage differ by material. Bark holds its depth longer than compost, so use the compost rows for compost and the matching chart for bark or wood chips.