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Basalt chip chart calculator
Put your area, depth and waste allowance in: 500 square feet at 3 inches with 10% waste needs 550.00 square feet, 5.09 cubic yards exact, order 6 cubic yards.
★ CONSTRUCTION · MATERIALS · BASALT CHIP CHART
Basalt Chip Chart: 6 Cubic Yards for 500 Sq Ft at 3 Inches
On the defaults — 500 square feet at 3 inches deep with a 10% waste allowance — you need 550.00 square feet of coverage, 5.09 cubic yards exact, so order 6 cubic yards of basalt chips. This is the BASALT CHIP version of the coverage chart — the granite-chip-chart page is the GRANITE CHIP version — 500 square feet at 2 inches with 10% waste; the river-rock-chart page is the RIVER ROCK version — 400 square feet at 2 inches with 10% waste; the pea-gravel-chart page is the PEA GRAVEL version — 300 square feet at 3 inches with 10% waste; and the slate-chip-chart page is the SLATE CHIP version — 400 square feet at 3 inches with 10% waste.
What does 5.09 cubic yards of basalt chips mean?
It means that a 500-square-foot bed at 3 inches deep needs 550.00 square feet of coverage once a 10% waste allowance is added, and one cubic yard of basalt chips covers 108 square feet at that depth, so the exact figure is 5.09 cubic yards and the order is 6 cubic yards. The two steps are the whole story in miniature: the waste step turns the measured area into the area you must actually cover, and the coverage step turns that area into yards. The part people get wrong is ordering the exact figure: 5.09 yards cannot be delivered as a fraction by most suppliers, and rounding down to 5 yards leaves 0.09 yards — about 10 square feet — uncovered, which sounds small until the thin patch is the one by the front door. The other part people get wrong is skipping the waste allowance: 500 square feet at 3 inches with no waste is 4.63 yards, which still orders 5, but on a larger bed the same omission can drop the order a full yard short.
Three things to check before you trust the number
Is 500 square feet really the bed, or the whole garden? Five hundred square feet is the ground the basalt chips actually cover, and it is the figure the whole calculation turns on: the 600-square-foot branch needs 6.11 yards against the 5.09 headline, so 100 extra square feet are 1.02 yards and one whole extra yard on the order. Measure length times width of the bed itself, and leave paths, planting holes, and edging strips out of the area — every square foot counted twice is coverage bought twice.
Is 3 inches really the depth, or the depth at the middle? Three inches is the finished depth across the whole bed, and it is the figure the coverage turns on: the 2-inch branch needs 3.40 yards against the 5.09 headline, so one inch less is 1.69 yards on this bed. A bed that is 3 inches at the edges and 4 inches in the dips averages deeper than 3 inches — measure the depth in several places and use the honest average, not the shallowest reading.
Is 10% waste right for your ground? Ten percent is the allowance for spreading loss, uneven ground, and edging gaps, and it is the figure the needed area turns on: the 0%-waste branch needs 4.63 yards against the 5.09 headline, so the waste line is 0.46 yards on this bed. Use 0% only for a perfectly flat, measured area; uneven ground, a long wheelbarrow haul, or a bed with many curves usually earns the full 10%, and a supplier minimum load may round the order up further.
Worked example
On the defaults: 500 square feet, 3 inches deep, 10% waste.
- Coverage per cubic yard: 324 ÷ 3 is 108 square feet.
- Needed area: 500 × 1.10 is 550.00 square feet.
- Exact cubic yards: 550.00 ÷ 108 is 5.09.
- Order: 5.09 rounded up is 6 cubic yards — never rounded down.
And the other way: the area behind 5.09 cubic yards is 500 square feet, the depth behind 5.09 cubic yards is 3 inches, and the waste behind 5.09 cubic yards is 10%. With 0 square feet the model honestly shows 0.00 cubic yards and an order of 0, because a bed with no area needs no basalt chips — an edge that shows the area is entered independently of the depth. And 108 square feet at 3 inches with 0% waste lands exactly on 1.00 cubic yard and orders exactly 1, not 2, because an exact integer is already a whole load.
Basalt chip lookup table
Every row below is the same model at 10% waste: needed area is the area times 1.10, coverage is 324 divided by depth, and the order is the exact figure rounded up. Find your area and depth, read across, and order the figure in the last column — do not round down, because a short load leaves the bed thin at the far end.
| Area (sq ft) | Depth (inches) | Needed area (sq ft) | Exact cubic yards | Order |
|---|---|---|---|---|
| 150 | 1 | 165.00 | 0.51 | 1 cubic yard |
| 150 | 2 | 165.00 | 1.02 | 2 cubic yards |
| 150 | 3 | 165.00 | 1.53 | 2 cubic yards |
| 150 | 4 | 165.00 | 2.04 | 3 cubic yards |
| 300 | 1 | 330.00 | 1.02 | 2 cubic yards |
| 300 | 2 | 330.00 | 2.04 | 3 cubic yards |
| 300 | 3 | 330.00 | 3.06 | 4 cubic yards |
| 300 | 4 | 330.00 | 4.07 | 5 cubic yards |
| 450 | 1 | 495.00 | 1.53 | 2 cubic yards |
| 450 | 2 | 495.00 | 3.06 | 4 cubic yards |
| 450 | 3 | 495.00 | 4.58 | 5 cubic yards |
| 450 | 4 | 495.00 | 6.11 | 7 cubic yards |
| 600 | 1 | 660.00 | 2.04 | 3 cubic yards |
| 600 | 2 | 660.00 | 4.07 | 5 cubic yards |
| 600 | 3 | 660.00 | 6.11 | 7 cubic yards |
| 600 | 4 | 660.00 | 8.15 | 9 cubic yards |
Every branch, checked
- 500 square feet, 3-inch depth, 0% waste: 500 square feet, 3-inch depth, 0% waste: 4.63 cubic yards exact — order 5 cubic yards.
- 500 square feet, 2-inch depth, 10% waste: 500 square feet, 2-inch depth, 10% waste: 3.40 cubic yards exact — order 4 cubic yards.
- 600 square feet, 3-inch depth, 10% waste: 600 square feet, 3-inch depth, 10% waste: 6.11 cubic yards exact — order 7 cubic yards.
- 250 square feet, 3-inch depth, 10% waste: 250 square feet, 3-inch depth, 10% waste: 2.55 cubic yards exact — order 3 cubic yards.
The reverses, worked backwards
- Area behind 5.09 cubic yards: 500 sq ft — at 500 sq ft the figures are 5.09 cubic yards exact — order 6 cubic yards.; at the lower neighbor the figures are 4.58 cubic yards exact — order 5 cubic yards.; at the upper neighbor the figures are 5.60 cubic yards exact — order 6 cubic yards..
- Depth behind 5.09 cubic yards: 3 inches — at 3 inches the figures are 5.09 cubic yards exact — order 6 cubic yards.; at the lower neighbor the figures are 4.24 cubic yards exact — order 5 cubic yards.; at the upper neighbor the figures are 5.94 cubic yards exact — order 6 cubic yards..
- Waste behind 5.09 cubic yards: 10% waste — at 10% waste the figures are 5.09 cubic yards exact — order 6 cubic yards.; at the lower neighbor the figures are 4.86 cubic yards exact — order 5 cubic yards.; at the upper neighbor the figures are 5.32 cubic yards exact — order 6 cubic yards..
What the defaults assume
The defaults are 500 square feet at 3-inch depth with 10% waste, so the headline is one modest basalt chip bed — a path border, a drainage strip, or a small garden bed. The model is a multiplication and a division: the needed area is area times the waste factor, the coverage per cubic yard is 324 divided by depth in inches, and the exact figure is needed area divided by coverage, rounded up to order. The area reverse is checked at 50 square feet either side, because 50 square feet at 3 inches with 10% waste is 0.51 yard; the depth reverse is checked at 0.5 inches either side, because half an inch either way moves the coverage by a wide margin at shallow depths; the waste reverse is checked at 5% either side, because 5% of 500 square feet is 25 square feet, or 0.23 yard. The model does not include chip size, moisture weight, compaction, or delivery minimums — a supplier may round an order of 6 cubic yards up to a minimum load, and wet chips weigh far more than dry chips per yard.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Coverage per cubic yard | 324 ÷ depth in inches | 108 sq ft — 324 ÷ 3, one cubic yard covers 108 square feet at 3 inches. |
| Needed area | area × (1 + waste ÷ 100) | 550.00 sq ft — 500 × 1.10. |
| Exact cubic yards | needed area ÷ coverage per cubic yard | 5.09 — 550.00 ÷ 108. |
| Order | exact cubic yards rounded up | 6 cubic yards — 5.09 rounded up, never down. |
| 500 square feet, 3-inch depth, 0% waste | same model | 4.63 cubic yards exact — order 5 cubic yards. |
| 500 square feet, 2-inch depth, 10% waste | same model | 3.40 cubic yards exact — order 4 cubic yards. |
| 600 square feet, 3-inch depth, 10% waste | same model | 6.11 cubic yards exact — order 7 cubic yards. |
| 250 square feet, 3-inch depth, 10% waste | same model | 2.55 cubic yards exact — order 3 cubic yards. |
| Area behind 5.09 cubic yards | reverse | 500 sq ft: 5.09 cubic yards exact — order 6 cubic yards. |
| Depth behind 5.09 cubic yards | reverse | 3 inches: 5.09 cubic yards exact — order 6 cubic yards. |
| Waste behind 5.09 cubic yards | reverse | 10% waste: 5.09 cubic yards exact — order 6 cubic yards. |
| 0 square feet | same model | 0.00 cubic yards exact — order 0 cubic yards. |
| Negative area | same model | Area — 0 or more. |
| Zero depth | same model | Depth — more than 0. |
| Negative waste | same model | Waste allowance — 0 or more. |
| 108 square feet, 0% waste | same model | 1.00 cubic yards exact — order 1 cubic yard. |
Who uses this
- A homeowner ordering basalt chips for a bed — 500 square feet at 3 inches is 5.09 yards exact and 6 on the order, with the lookup table covering the next bed size without a second calculation.
- A landscaper quoting a job — the branches price a deeper bed or a larger area at once, so a quote change can be costed before it is agreed.
- A contractor checking a delivery — the reverses recover the area, depth, or waste behind any quoted yardage, so a short load can be challenged with numbers.
- A garden-center shopper comparing quotes — the exact figure separates the material from the delivery charge, so two quotes can be compared yard for yard.
Accuracy & limitations
Figures are the model’s own arithmetic on the numbers you type, computed from unrounded values and displayed rounded HALF_UP to 2dp. The main limitation is the inputs, not the arithmetic: whether the area is the bed alone, whether the depth is an honest average, and whether the waste allowance fits the ground are all judgement calls, and this page prices the figures you enter without checking them. This page is a calculation tool, not a landscaping or construction specification.
Cite this calculator
Basalt chips for 500 sq ft at 3 inches with 10% waste need 550.00 sq ft, 5.09 cubic yards exact, order 6 cubic yards, plus a 16-row lookup table. Source: Bright Side Kit, https://brightoolbox.com/basalt-chip-chart/, accessed 29 October 2026.
Frequently asked questions
What are basalt chips used for in a garden bed?
Crushed basalt chips are used as a decorative ground cover, a drainage layer, and a path surface: they drain well, suppress weeds under a bed, and settle into a firm, dark layer. This chart prices them by volume, the way bulk suppliers sell them.
How deep should a basalt chip bed be?
Three inches is a solid depth for a bed that takes weight, and it is the default here; a purely decorative bed can be 2 inches, and a parking strip is usually 4 inches, and the lookup table prices those depths directly. A thinner layer shows the ground through it, so depth is worth measuring honestly.
Why order 6 cubic yards when the exact figure is 5.09?
Because suppliers deliver whole yards, and rounding down leaves part of the bed uncovered: 0.09 yards short is about 10 square feet at 3 inches, and the shortfall always shows at the far end of the bed. The leftover from rounding up spreads thinner at the edges or tops up the next bed.
Do I need the 10% waste allowance?
On flat, measured ground you can use less, but spreading loss, uneven ground, and edging gaps consume real material, and the allowance is only 0.46 yards on this bed. The 0%-waste branch is shown so you can compare the two figures before deciding.
What if my supplier sells by the ton, not the yard?
Ask the supplier for the tons-per-yard conversion for their basalt chips before ordering, because density varies by chip size and moisture. This chart works in cubic yards, so convert the exact figure — 5.09 yards — with the supplier’s own factor, not a guess.
Do basalt chips compact after delivery?
Yes, and the chart does not model it: freshly spread chips settle under rain and foot traffic, so a bed can look thinner after a few weeks. Ordering the rounded-up figure, rather than the exact one, is the usual buffer against that settling.