What does 113.06 cubic yards of koa bark mulch mean?
It means a 11100 square foot bed, once the 10% waste allowance is added, needs 12,210.00 square feet of cover at 3 inches deep — 3,052.50 cubic feet, which is 113.06 cubic yards. Because mulch is sold by the whole yard, you order 114 cubic yards: the exact figure sits 0.94 yards below the next whole yard, so the order carries 0.94 yards of headroom for spillage and uneven ground. At 3 inches, one cubic yard covers 108.0 square feet, so the same bed at 2 inches would need only 75.37 yards, and at 4 inches it would need 150.74 yards.
Output · formula · meaning
| Output | Formula | What it means |
|---|
| Area needed | area × (1 + waste ÷ 100) | 12,210.00 sq ft — 11100 × 1.10. |
| Volume in cubic feet | area needed × depth ÷ 12 | 3,052.50 cubic feet — 12,210.00 × 3 ÷ 12. |
| Exact volume | area needed × depth ÷ 324 | 113.06 cubic yards — 12,210.00 × 3 ÷ 324. |
| Order quantity | round exact volume up to a whole yard | 114 cubic yards — the next whole yard above 113.06. |
| 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) | 11100 sq ft — 113.06 × 324 ÷ 3 ÷ 1.10, rounded. |
| Depth behind a target volume | area needed × depth ÷ 324, solved for depth | 3 inches — the depth that turns 12,210.00 sq ft into 113.06 yards. |
| Waste behind a target volume | target volume × 324 ÷ depth ÷ area − 1, as a percent | 10% — the allowance that turns 11100 sq ft into 12,210.00 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: koa bark is reddish-brown and furrowed, so it lays into a dense layer that holds moisture well, but a dense layer thins as it settles and the thin spots need topping up through the season. Third, do not skip the waste allowance on koa bark: even a well-laid reddish-brown bark scatters at the edges, and spillage and uneven ground still eat into the load, so the 10% allowance is the difference between finishing the bed and running short with the truck already gone. The headline order of 114 yards carries 0.94 yards of headroom, which covers ordinary spillage on a bed like this one. The koa itself is a fast-growing Hawaiian acacia, famous for its golden-brown wood used in ukuleles and fine furniture — the bark mulch comes from its bark and mill trimmings, not from the timber.
Worked example
Area 11100 sq ft, depth 3 inches, waste 10%. Area needed: 11100 × 1.10 = 12,210.00 sq ft. Exact volume: 12,210.00 × 3 ÷ 324 = 113.06 cubic yards. Order: round 113.06 up to 114 cubic yards. Drop the waste to 0% and the exact volume falls to 102.78 yards, order 103; raise the waste to 5% and it is 107.92 yards, order 108; raise it to 15% and it is 118.19 yards, order 119. Drop the depth to 2 inches and it falls to 75.37 yards, order 76; raise it to 4 inches and it climbs to 150.74 yards, order 151. Depth moves the answer faster than waste does, because every inch adds a full layer across the whole bed.
Koa bark 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 |
|---|
| 300 | 2 | 330.00 | 2.04 | 3 cubic yards |
| 300 | 3 | 330.00 | 3.06 | 4 cubic yards |
| 600 | 2 | 660.00 | 4.07 | 5 cubic yards |
| 600 | 3 | 660.00 | 6.11 | 7 cubic yards |
| 800 | 3 | 880.00 | 8.15 | 9 cubic yards |
| 800 | 4 | 880.00 | 10.86 | 11 cubic yards |
| 1100 | 2 | 1,210.00 | 7.47 | 8 cubic yards |
| 1100 | 3 | 1,210.00 | 11.20 | 12 cubic yards |
| 1300 | 2 | 1,430.00 | 8.83 | 9 cubic yards |
| 1500 | 3 | 1,650.00 | 15.28 | 16 cubic yards |
| 1600 | 3 | 1,760.00 | 16.30 | 17 cubic yards |
| 1600 | 4 | 1,760.00 | 21.73 | 22 cubic yards |
| 1800 | 2 | 1,980.00 | 12.22 | 13 cubic yards |
| 2200 | 3 | 2,420.00 | 22.41 | 23 cubic yards |
| 2600 | 3 | 2,860.00 | 26.48 | 27 cubic yards |
| 3200 | 2 | 3,520.00 | 21.73 | 22 cubic yards |
Every branch, checked
A 11100 square foot bed at 3-inch depth with 0% waste gives 102.78 cubic yards exact, order 103 cubic yards. The same bed at 2-inch depth with 10% waste gives 75.37 cubic yards exact, order 76 cubic yards. A 10900 square foot bed at 3-inch depth with 10% waste gives 111.02 cubic yards exact, order 112 cubic yards. The same bed at 4-inch depth with 10% waste gives 150.74 cubic yards exact, order 151 cubic yards. Each branch changes exactly one input, so the difference from 113.06 isolates that input.
The reverses, worked backwards
The area behind 113.06 cubic yards is 11100 sq ft: at 10900 sq ft the figures are 111.02 cubic yards exact, order 112 cubic yards, and at 11300 sq ft they are 115.09 cubic yards exact, order 116 cubic yards. The depth behind 113.06 cubic yards is 3 inches: at 2 inches the figures are 75.37 cubic yards exact, order 76 cubic yards, and at 4 inches they are 150.74 cubic yards exact, order 151 cubic yards — one inch either way moves the order by about 37.69 yards. The waste behind 113.06 cubic yards is 10%: at 5% the figures are 107.92 cubic yards exact, order 108 cubic yards, and at 15% they are 118.19 cubic yards exact, order 119 cubic yards.
What the defaults assume
The defaults assume a flat 11100 square foot bed, a uniform 3-inch layer, and a 10% waste allowance. Real koa bark beds are rarely flat: paths and tree trunks eat into the area, and reddish-brown bark at the edges washes into the lawn, 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 dressing beds and paths with koa bark: the 11100 square foot headline is a large garden bed or a long drive, and the table covers everything from a 300 square foot border to a 3200 square foot yard. A landscaper quoting a koa bark job: the waste column protects the quote, and the order column is the number given to the supplier. A homeowner laying koa bark on a path: the 3-inch rows are the bed depths, and the 2-inch rows are the path 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 the coarse bark settles, or a skipped waste allowance will each move the answer by exactly the amount of the error, every load. The model does not include bark washing at the edges, delivery minimums, or the gaps between coarse bark pieces — 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
Koa bark mulch 11100 sq ft at 3-inch depth with 10% waste needs 12,210 sq ft, 113.06 cubic yards exact, order 114 yards. Free calculator, plus 16 rows. Source: Bright Side Kit, https://brightoolbox.com/koa-bark-mulch-chart/, accessed 1 November 2026 (2026-11-01).
Frequently asked questions
Why does the table apply waste to the area first?
Because waste is lost cover: spillage, scattering 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 koa bark mulch really be?
Three inches is the standard bed layer on this page, and 2 inches suit paths and top-ups. Koa bark is reddish-brown and furrowed, so a 3-inch spread settles and thins over the season; if thin spots appear, top them up rather than re-laying the whole bed.
Does koa bark mulch introduce weed seeds?
Koa bark is organic, so a load can carry a few weed seeds; weeds can still root in the dust and debris that collects on top of it, so use fabric underneath and clear the debris. 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 114 yards when the exact figure is 113.06?
Because mulch is sold by the whole yard, and 113.06 rounds up to 114 — the order carries 0.94 yards of headroom for spillage and uneven ground. That headroom is the buffer the exact figure does not have.
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. Koa bark settles as its deep furrows break down, so use the koa bark rows for koa bark and the matching chart for stone or wood chips.