Stone base under concrete

Concrete Base Gravel Calculator

Estimate crushed stone or gravel under a concrete slab from slab length, width, base depth, compaction allowance, waste, and material density. It bridges concrete takeoff and aggregate ordering without changing the slab concrete volume.

Units

Slab length (ft)Slab width (ft)Base depth (in)Compaction factor Waste / edge loss (%)Stone density (tons/yd³)Cost per weight unit ($/ton)

Gravel volume

Estimated weight

Slab area

Rough cost

Base depth is site-specific

This is an aggregate quantity estimate. Soil, drainage, compaction, frost, vapor barrier details, reinforcement, slab use, and local practice decide the actual base section.

Android App

Need gravel base under concrete estimates hands-free?

Use the Android app when you need voice input, offline use, material lists, or PDF export. Free, no ads, no accounts.

Get the Free App Free. Built for Android phones. Donations welcome.

Saved you a mistake? Support VibeCalc

Concrete Calculator

Estimate the slab concrete volume after setting the base section.

Gravel Calculator

Estimate broader driveway, path, or landscape gravel quantities.

Rebar Calculator

Plan slab reinforcement after the base and concrete quantities are known.

View all

Concrete base gravel formula

Base yd³ = length × width × depth inches ÷ 324

Order yd³ = base yd³ × compaction factor × (1 + waste %)

Tons = order yd³ × density tons per yd³

Sample takeoff

A 20 ft by 12 ft slab with a 4 in stone base, 1.10 compaction factor, 5% waste, and 1.4 tons per yd³ needs about 3.42 yd³, or 4.8 tons, of gravel.A 6 m by 3.6 m slab with a 100 mm stone base, 1.10 compaction factor, 5% waste, and 1.7 t/m³ needs about 2.49 m³, or 4.2 tonnes, of gravel.

Concrete Base Gravel Calculator FAQ

How much gravel do I need under a concrete slab?+

Multiply slab length by width by base depth, convert to cubic yards or cubic meters, then add compaction and waste allowances.Multiply slab length by width by base depth, convert to cubic yards or cubic meters, then add compaction and waste allowances.

What depth should I use for slab gravel?+

Four inches is a common quick planning value, but soil, drainage, frost, loads, and local practice can require more or a different base detail.Four inches is a common quick planning value, but soil, drainage, frost, loads, and local practice can require more or a different base detail.

Is this the same as the concrete volume?+

No. This estimates aggregate under the slab. Use the concrete calculator for the concrete placed above the base.No. This estimates aggregate under the slab. Use the concrete calculator for the concrete placed above the base.