Does the gravel calculator assume a 50 mm depth?

No. Enter the actual depth chosen for the gravel product and intended use. Stone size and supplier guidance can change the appropriate depth.

What bulk density should I use for gravel?

Use current supplier or product data for the gravel you intend to buy. The calculator does not impose one universal density.

Does the calculator assume a standard bulk bag size?

No. In supplier-coverage mode, enter the exact stated coverage per bag and the depth used for that coverage. Bag weight is optional and should come from the supplier.

Landscaping · loose gravel quantity

Gravel Calculator

Start with the actual area and gravel depth to get cubic metres and litres. Then convert to tonnes or whole supplier bags only from product information you actually have.

0% extra by defaultNo fixed gravel depthNo generic density or bag size

Landscaping illustration for the Gravel Calculator

Measure the gravel layer, then choose the supplier conversion

The base calculation is simply area × chosen depth. For ordering, use either a real supplier/product density or the coverage stated for the exact bag you intend to buy.

How do you want to convert the gravel volume? Supplier density → tonnesUse a current tonnes-per-cubic-metre figure for the exact gravel product. Supplier bag coverageUse stated m² coverage at a stated depth; add bag weight only if you want nominal tonnes.

Actual area to cover

m²

Measure the footprint of the finished gravel layer.

Chosen gravel depth

Use the depth appropriate to the exact stone size, intended use and supplier guidance.

Supplier / product bulk density

t/m³

Enter a real current figure for the gravel you are ordering; do not assume 1.6 t/m³.

Extra ordering allowance

Optional. Starts at 0%; choose an allowance only if the job needs one.

No compaction or settlement factor is hidden in the result. This tool calculates the loose gravel layer you specify. It does not invent sub-base depth, product density, bag size or a universal spreading depth.

Enter the actual area, chosen gravel depth and supplier conversion.The results will keep base volume, optional allowance and purchasing conversion separate.

How the gravel quantity is built

01Measure the surface

Use the actual square metres to receive gravel.

02Choose the product depth

Stone size and intended use affect the appropriate spreading depth.

03Convert only with real product data

Use supplier density for tonnes or stated coverage for bags.

Core formula

Base gravel volume = area (m²) × depth (mm ÷ 1,000). Litres = m³ × 1,000.

Why there is no 50 mm default

UK suppliers themselves publish different spreading depths for different stone sizes. A commonly recommended depth for smaller gravel or chippings may not be appropriate for larger pebbles or cobbles, so this calculator asks for the depth that applies to the product and job instead of silently choosing one.

Why density and bag size start blank

Bulk density, bag weight and coverage vary by aggregate and supplier. Even products sold as “bulk bags” are not one universal weight or one universal square-metre coverage. Use the information for the exact product being ordered.

Worked calculation — volume only

If an area is 20 m² and the chosen gravel depth is 40 mm, the base volume is 0.800 m³, or 800 litres. No tonnes or bags should be inferred until a real density or supplier coverage is supplied.

What the two purchasing modes mean

Density → tonnes

Multiply the calculated volume by the actual product density you enter. The calculator does not round to a delivery increment because quarry and merchant ordering units vary.

Coverage → whole bags

Convert the supplier’s m²-per-bag figure at its stated depth into an equivalent volume per bag, then round the final order up to whole bags.

Optional bag weight

If the exact bag weight is known, the calculator can show the nominal tonnes represented by the final whole bags. It does not use bag weight as a substitute for coverage.

Quantity estimate, not construction design. This calculator does not decide a suitable gravel type, surface depth, sub-base, edging, drainage, compaction or installation method. Check the chosen product, intended use and supplier guidance before ordering.

Continue the aggregate workflow

Layer belowPatio Sub-Base CalculatorKeep a compacted structural layer separate from loose decorative gravel.Known tonnageAggregate Bag CalculatorAlready know the tonnes required? Convert that requirement using the actual bag weight.General aggregateAggregate Tonnage CalculatorUse the broader area × depth × density workflow for other aggregates.ReferenceAggregate Bulk Density GuideUnderstand why m³ cannot become tonnes without a density assumption.Ordering guideAggregate Ordering GuideKeep cubic metres, tonnes and bags separate when checking a supplier quote.

Frequently asked questions

How deep should gravel be?

There is no single depth for every gravel product or use. Use the depth appropriate to the exact stone size, location and supplier or installation guidance.

What density should I use?

Use current product or supplier information for the actual gravel. Moisture, grading and particle shape can affect bulk density.

Does a bulk bag always weigh 800 kg?

No. Bag weights and tolerances vary by supplier and product. Enter the stated weight only when it applies to the exact bag you intend to buy.