How Much Gravel for a Patio Base? Volume Before Supplier Conversions
Worked scenarios are illustrative composites. Our editorial pen name and method.
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Gravel for a patio base is where a simple “length times width times depth” quietly turns into three different numbers — the compacted volume you designed, the looser volume the truck delivers, and the tons the supplier actually bills. Miss the steps between them and you’ll either come up short mid-project or pay for a heaped pile you can’t use. The trick is to calculate them in order and let the supplier’s own conversion factors, not a rule of thumb, do the last two steps.
Step one: the compacted design volume
Start with the base you actually want after it’s tamped down. For a worked footprint of 10 ft × 20 ft and a hypothetical specified compacted depth of 4 inches:
10 × 20 × (4 ÷ 12) = 66.67 cu ft
66.67 ÷ 27 = 2.47 cubic yards compacted
That 4-inch depth is an example, not a recommendation — Belgard notes base depth is influenced by soil type and application, and its residential guidance discusses a range rather than one universal design. Local climate, drainage, soil, loading and code can all change it:
Step two: don’t hard-code a compaction allowance
A loose-to-compacted conversion is material- and process-specific. Do not add a universal 20–25% allowance. Obtain a suitable factor from the supplier or project designer and keep it separate from the measured compacted volume.
For sensitivity only — to show the formula, not to pick a number:
| Loose-volume factor | Loose yards from 2.47 compacted |
|---|---|
| 1.10 | 2.72 yd³ |
| 1.20 | 2.96 yd³ |
| 1.25 | 3.09 yd³ |
These rows demonstrate the math; they don’t tell you which factor applies to your gravel. Then round to the supplier’s order increment as a commercial step, after you’ve confirmed the material and factor.
Step three: tons need the supplier’s density
Aggregate is usually sold by weight, so the last conversion is loose cubic yards to tons — and that depends on the material’s density, which only the supplier can give you accurately:
Tons = loose cubic yards × supplier tons per cubic yard
Using 2.96 loose yd³ from the 1.20 row above:
| Supplier density | Tons |
|---|---|
| 1.35 tons/yd³ | 4.00 |
| 1.50 tons/yd³ | 4.44 |
| 1.65 tons/yd³ | 4.89 |
Moisture, rock type, gradation and scale practice all move this. That’s why a delivered weight ticket can differ from your volume estimate without either being wrong — one measures mass, the other space, and the bridge between them is a density you should get from the supplier.
What this calculation does not decide
Quantity math follows the design; it can’t create it. This page does not choose your base depth or aggregate spec, your excavation, drainage slope, frost or expansive-soil treatment, geotextile use, lift thickness, compaction target, edge restraint or bedding. Belgard’s guidance, for instance, calls for base material placed in layers with thickness tied to compaction method and use. Get the system from the chosen paver’s instructions first.
Ordering checklist
- Get the project-specific compacted depth and material spec.
- Measure net area and calculate compacted cubic volume.
- Ask the supplier for the loose-volume and tons-per-yard factors for that material.
- Enter delivery increments, minimum order and price separately.
- Confirm the result with the supplier before a truck rolls.
Loose-volume and compaction errors
- Ordering the compacted volume as-is. Loose gravel settles; apply the supplier’s factor.
- Hard-coding a 20% fluff allowance. It varies by material and compaction; ask.
- Assuming a generic tons-per-yard. Density is material-specific — get the supplier’s number.
- Expecting the weight ticket to match your volume exactly. Different measures; moisture moves it.
Quantity arithmetic is not a patio design
This is quantity arithmetic, not construction or engineering advice. Base depth, drainage and compaction are design decisions for the paver system and site conditions — follow those, and let the supplier’s conversions settle loose volume and tonnage.
The mulch, soil and gravel calculator makes tons per cubic yard an editable field; its prefilled material values are scenario defaults, so enter the supplier’s number or set it to zero to omit weight. These are general-information estimates, not construction advice.