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Onyx mulch chart
Put your bed area, onyx mulch depth and waste allowance in: 6000 sq ft at 3 inches with 10% waste needs 6,600.00 sq ft, 61.11 cubic yards exact — order 62 cubic yards.
★ CONSTRUCTION · MULCH · ONYX MULCH CHART
Onyx Mulch Chart: 6000 Sq Ft, 3 Inches, Order 62 Yards
On the defaults — a 6000 square foot bed at 3 inches deep with a 10% waste allowance — you need 6,600.00 square feet of cover, 61.11 cubic yards exact, so order 62 cubic yards. This is the ONYX version — the mulch chart for onyx, a dark, banded stone that drains well, holds its colour and never breaks down — the travertine-mulch-chart page is the TRAVERTINE version, the quartzite-mulch-chart page is the QUARTZITE version, and the mulch-chart page is the GENERAL version for any loose mulch.
What does 61.11 cubic yards of onyx mulch mean?
It means a 6000 square foot bed, once the 10% waste allowance is added, needs 6,600.00 square feet of cover at 3 inches deep — 1,650.00 cubic feet, which is 61.11 cubic yards. Because mulch is sold by the whole yard, you order 62 cubic yards: the exact figure sits 0.89 yards below the next whole yard, so the order carries 0.89 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 40.74 yards, and at 4 inches it would need 81.48 yards.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Area needed | area × (1 + waste ÷ 100) | 6,600.00 sq ft — 6000 × 1.10. |
| Volume in cubic feet | area needed × depth ÷ 12 | 1,650.00 cubic feet — 6,600.00 × 3 ÷ 12. |
| Exact volume | area needed × depth ÷ 324 | 61.11 cubic yards — 6,600.00 × 3 ÷ 324. |
| Order quantity | round exact volume up to a whole yard | 62 cubic yards — the next whole yard above 61.11. |
| 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) | 6000 sq ft — 61.11 × 324 ÷ 3 ÷ 1.10, rounded. |
| Depth behind a target volume | area needed × depth ÷ 324, solved for depth | 3 inches — the depth that turns 6,600.00 sq ft into 61.11 yards. |
| Waste behind a target volume | target volume × 324 ÷ depth ÷ area − 1, as a percent | 10% — the allowance that turns 6000 sq ft into 6,600.00 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: onyx does not break down, so the layer you spread is the layer that stays — but the stones scatter onto paths and lawns when raked or walked on, so edge the bed if you want the depth to hold. Third, do not skip the waste allowance on onyx: the stones are dense and smooth, and settle together, so they stay put better than round gravel on slopes, but spillage at the edges 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 62 yards carries 0.89 yards of headroom, which covers ordinary spillage on a bed like this one.
Worked example
Area 6000 sq ft, depth 3 inches, waste 10%. Area needed: 6000 × 1.10 = 6,600.00 sq ft. Exact volume: 6,600.00 × 3 ÷ 324 = 61.11 cubic yards. Order: round 61.11 up to 62 cubic yards. Drop the waste to 0% and the exact volume falls to 55.56 yards, order 56; raise the waste to 5% and it is 58.33 yards, order 59; raise it to 15% and it is 63.89 yards, order 64. Drop the depth to 2 inches and it falls to 40.74 yards, order 41; raise it to 4 inches and it climbs to 81.48 yards, order 82. Depth moves the answer faster than waste does, because every inch adds a full layer across the whole bed.
Onyx 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 | 3 | 825.00 | 7.64 | 8 cubic yards |
| 750 | 4 | 825.00 | 10.19 | 11 cubic yards |
| 1000 | 2 | 1,100.00 | 6.79 | 7 cubic yards |
| 1000 | 3 | 1,100.00 | 10.19 | 11 cubic yards |
| 1200 | 2 | 1,320.00 | 8.15 | 9 cubic yards |
| 1400 | 3 | 1,540.00 | 14.26 | 15 cubic yards |
| 1500 | 3 | 1,650.00 | 15.28 | 16 cubic yards |
| 1500 | 4 | 1,650.00 | 20.37 | 21 cubic yards |
| 1750 | 2 | 1,925.00 | 11.88 | 12 cubic yards |
| 2000 | 3 | 2,200.00 | 20.37 | 21 cubic yards |
| 2500 | 3 | 2,750.00 | 25.46 | 26 cubic yards |
| 3000 | 2 | 3,300.00 | 20.37 | 21 cubic yards |
Every branch, checked
A 6000 square foot bed at 3-inch depth with 0% waste gives 55.56 cubic yards exact, order 56 cubic yards. The same bed at 2-inch depth with 10% waste gives 40.74 cubic yards exact, order 41 cubic yards. A 5750 square foot bed at 3-inch depth with 10% waste gives 58.56 cubic yards exact, order 59 cubic yards. A 6250 square foot bed at 3-inch depth with 10% waste gives 63.66 cubic yards exact, order 64 cubic yards. Each branch changes exactly one input, so the difference from 61.11 isolates that input.
The reverses, worked backwards
The area behind 61.11 cubic yards is 6000 sq ft: at 5750 sq ft the figures are 58.56 cubic yards exact, order 59 cubic yards, and at 6250 sq ft they are 63.66 cubic yards exact, order 64 cubic yards. The depth behind 61.11 cubic yards is 3 inches: at 2 inches the figures are 40.74 cubic yards exact, order 41 cubic yards, and at 4 inches they are 81.48 cubic yards exact, order 82 cubic yards — one inch either way moves the order by about 20.4 yards. The waste behind 61.11 cubic yards is 10%: at 5% the figures are 58.33 cubic yards exact, order 59 cubic yards, and at 15% they are 63.89 cubic yards exact, order 64 cubic yards — waste moves the exact volume, and at 15% it lifts the order to 62 yards.
What the defaults assume
The defaults assume a flat 6000 square foot bed, a uniform 3-inch layer, and a 10% waste allowance. Real onyx beds are rarely flat: slopes shed stones downhill, paths and tree trunks eat into the area, and loose stones wander 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 with onyx: the 6000 square foot headline is a large garden bed, and the table covers everything from a 250 square foot border to a 3000 square foot yard. A landscaper quoting a onyx job: the waste column protects the quote, and the order column is the number given to the supplier. A homesteader spreading bulk onyx on paths: 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 stones scatter, or a skipped waste allowance will each move the answer by exactly the amount of the error, every load. The model does not include stones scattering into lawns, delivery minimums, or compaction — 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
Onyx mulch 6000 sq ft at 3-inch depth with 10% waste needs 6,600.00 sq ft, 61.11 cubic yards exact, order 62 yards. Free calculator, plus 16-row table. Source: Bright Side Kit, https://brightoolbox.com/onyx-mulch-chart/, accessed 31 October 2026 (2026-10-31).
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 onyx mulch really be?
Three inches is the standard bed layer on this page, and 2 inches suit paths and top-ups. Onyx does not break down, so a 3-inch spread stays 3 inches; if stones scatter, rake them back or top up the thin spots.
Does onyx mulch introduce weed seeds?
Onyx is mineral, so it carries no weed seeds at all; 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 62 yards when the exact figure is 61.11?
Because mulch is sold by the whole yard, and 61.11 rounds up to 62 — the order carries 0.89 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. Onyx does not settle like bark, so use the onyx rows for onyx and the matching chart for bark or wood chips.