Gravel calculator

How this calculator works

It multiplies the area by the depth to get the volume, adds an allowance for compaction, then converts volume to weight with the gravel’s density, because quarries and yards sell bulk stone by the ton. Bags are counted by volume in the US and by weight in metric markets.

The default density is 1.4 tons per cubic yard (1.6 tonnes per m³), a typical figure for crushed stone and pea gravel. Your supplier can give you the exact number for the stone you choose.

Worked example

A 20′ × 10′ parking pad at 3″ deep holds 200 × 3 ÷ 12 = 50 cu ft, or 1.85 cu yd. With 10% for compaction that is 2.04 cu yd; at 1.4 tons per cu yd it weighs 2.85 tons, so you order 3 tons. Fabric for 200 sq ft plus 10% overlap is 2 rolls of 150 sq ft.

Tips before you buy

• Paths need 2–3″ of gravel; driveways need 4″ or more over a compacted base.
• Angular crushed stone locks together and stays put; round pea gravel is comfortable underfoot but moves around.
• Install edging before you spread gravel so it stays on the path.
• Ask the supplier for the stone’s weight per cubic yard and enter it under Coverage and waste.

Questions

How much does a cubic yard of gravel weigh?

Most gravel and crushed stone weighs about 1.4 to 1.5 tons per cubic yard (roughly 1.5 to 1.7 tonnes per cubic metre). Wet stone and denser rock weigh more, so suppliers quote their own figure.

How many bags of gravel make a ton?

With 0.5 cu ft bags and stone at 1.4 tons per cubic yard, one ton is about 39 bags. In metric, a tonne is 40 bags of 25 kg.

Do I need landscape fabric under gravel?

It is not required, but a woven landscape fabric keeps gravel from sinking into the soil and slows weeds. Overlap the seams by several inches and pin them down before spreading the stone.

Why add extra for compaction?

Gravel settles and locks together once it is raked, driven on or compacted, so a loose pile covers less depth than its volume suggests. A 10% allowance keeps the finished layer at the depth you planned.