How to Use This Tool
Enter the area and the depth you want after compaction, then set the material. The compaction allowance and the density are both editable, because both vary by supplier and by how hard the base is rolled.
Compaction is why the arithmetic is not enough
Aggregate arrives loose, with air between the stones. Rolling or tamping it drives the fines into those voids, and the layer loses height. A base specified at 4 inches compacted typically needs about 5 inches of loose material, which is a 25 per cent allowance.
Different products behave differently. Well-graded crushed base with fines compacts the most, around 20 to 30 per cent. Single-size pea gravel barely compacts at all, closer to 10 per cent, because uniform round stones have nowhere to move to. Mulch and topsoil settle rather than compact, so the allowance there is about settlement over the first season.
area 25 x 20 = 500 sq ft
finished 500 x (4/12) / 27 = 6.17 cu yd
+25% compaction = 7.72 cu yd
x 1.40 ton/cu yd = 10.80 short tons
= 9.80 metric tonnes
Density varies more than the calculators admit
A cubic yard of crushed stone weighs roughly 1.35 to 1.45 tons; pea gravel is lighter, screened topsoil lighter again, and bark mulch is under half. Moisture moves all of these figures, sometimes by 10 per cent after rain, which is worth knowing if you are buying by weight from an uncovered stockpile.
The practical rule: if you are buying by the ton, ask the supplier for their density for that specific product rather than trusting a generic table. The number they give you goes in the density field.
Comparing quotes means converting units first
Quarries usually quote per ton. Landscape suppliers often quote per cubic yard. Bagged product is priced per bag, and a bag is commonly 0.5 cu ft, so it takes 54 bags to make a cubic yard — which is why bagged aggregate is around three times the bulk price.
Once delivery is added, the cheaper unit price frequently loses. A single delivery fee spread over a larger order is often the difference, so the comparison here includes it.
Short tons against metric tonnes
A short ton is 2,000 lb and a metric tonne is 2,205 lb, a 10 per cent gap. On a 10 ton order that is 1,000 lb of material, so it is worth confirming which one a quote means, particularly from a supplier that also sells to commercial customers.
What to add on top
Geotextile fabric under the base, edge restraint, and a separate bedding layer if you are laying pavers are all additional. This tool sizes the aggregate layer only.
