Gravel Calculator

Last updated: June 2026

Area length

Area width

Depth

Typical depths: path 40-50mm, decorative 30-40mm.

Material

Area

10 m²

Volume

0.5 m³

Weight

0.75 tonnes

Bulk bags

1 bags

Small bags

30 bags

Formula

Volume = length x width x depth in metres. Weight = volume x material density. Small bags assume 25kg and bulk bags assume 850kg.

About this calculator

Estimate gravel, pea gravel, crushed stone, topsoil, sand, or bark by area, depth, volume, tonnes, bulk bags, and 25kg bags. It is useful for paths, drive edges, garden borders, bases, and landscaping jobs.

Gravel volume and weight method

The calculator uses metric dimensions and practical UK planning assumptions. Results are estimates, so check product labels, site conditions, and supplier guidance before ordering materials.

area = length x width
volume = area x depth in metres
weight = volume x material density

How to use the gravel calculator

Choose the project type or measurement mode where the calculator offers one.
Enter all dimensions in metric units.
Add allowances such as coats, waste, pattern repeat, roll width, or bag size where relevant.
Review the main highlighted result first.
Check secondary results such as packs, bags, rolls, posts, or tin combinations.
Round up to supplier pack sizes and confirm the label coverage before buying.

Worked examples

Garden path gravel

Input: 5m x 2m area, 50mm depth, gravel at 1,500kg/m³

Calculation: Volume = 5 x 2 x 0.05 = 0.5m³. Weight = 0.5 x 1,500 = 750kg.

Result: About 0.75 tonnes, 1 bulk bag, or 30 small 25kg bags.

Bark mulch

Input: 10m² at 40mm depth, bark at 250kg/m³

Calculation: Volume = 10 x 0.04 = 0.4m³. Weight = 0.4 x 250 = 100kg.

Result: About 0.1 tonnes, but volume may matter more than weight for bark.

How deep should gravel be?

Decorative gravel is often around 30-40mm deep. Paths commonly use around 40-50mm. Driveways and load-bearing areas need proper sub-base design and should not rely on decorative gravel depth alone.

Bulk bag vs small bags

Small bags are convenient for small jobs and awkward access. Bulk bags are usually cheaper per kilogram but need delivery access and a place to unload.

Common mistakes

Mixing centimetres, millimetres, and metres without converting first.
Ordering exact quantities with no allowance for cuts, waste, damage, or uneven surfaces.
Forgetting that products are sold in tins, packs, bags, rolls, or boards rather than exact calculated quantities.
Using average deductions or coverage rates when the project has unusual shapes, textures, slopes, or access limits.
Not checking manufacturer instructions before final ordering.

Home improvement estimate disclaimer

This calculator is for general DIY planning only. It is not a substitute for a professional survey, structural design, building control advice, manufacturer instructions, or installer measurement.

Actual product coverage and pack sizes vary by supplier.
Site conditions can change material quantities.
Structural, roofing, electrical, gas, and regulated building work may need qualified advice.

Frequently asked questions

Why does material density matter?

Different materials weigh different amounts for the same volume. Bark is much lighter than gravel or sand.

How big is a bulk bag?

The calculator assumes 850kg as a practical bulk bag estimate. Actual bag weights vary by supplier and material.

Should I order extra gravel?

A small extra allowance can help with uneven ground, compaction, and future top-ups.

Does this include sub-base?

No. It estimates the selected top material only. Paths and driveways may need membrane and sub-base layers.

Can I use it for soil?

Yes, select topsoil. Remember soil can settle, and moisture content affects delivered weight.

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What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.