Gravel calculator UK
Work out gravel coverage for paths, borders and driveways across the UK in square metres, cubic metres, tonnes and bulk bags.
Project dimensions
Results in common UK units
| Calculated area | – |
|---|---|
| Depth used in calculation | – |
| Volume of gravel | – |
| Estimated weight | – |
| Approximate bulk bags | – |
| Approximate 25kg bags | – |
All figures are indicative and rounded; always check with your chosen UK aggregate supplier before placing an order.[web:1][web:5][web:7]
Quick reference: suggested depths
Depth varies with stone size and use. The table below reflects common UK practice for decorative aggregates and driveway gravel.[web:5][web:6][web:7][web:10]
| Project type | Typical gravel size | Suggested depth | Notes |
|---|---|---|---|
| Borders and decorative beds | 6–10mm | 30–40mm | Thin layer gives good coverage without burying plants.[web:5][web:6] |
| Garden paths | 10–14mm | 40–50mm | Comfortable to walk on, less likely to move underfoot.[web:5][web:6] |
| Driveways (cars and vans) | 14–20mm | 50–75mm | Greater depth helps resist rutting under vehicle tyres.[web:5][web:7][web:10] |
| Cobbles and larger pebbles | 40–50mm+ cobbles | 70–100mm | Extra depth allows rounded stones to sit securely.[web:5][web:10] |
How the gravel quantity is worked out
The calculation starts by turning your project area and gravel depth into a volume in cubic metres. The standard volume rule is:
Volume in cubic metres = area in square metres × depth in metres.[web:3][web:13]
A typical bulk density of loose gravel used in many UK calculators is about 1600–1700 kg per cubic metre, which is then divided by the weight of a bulk bag or small bag to give an approximate quantity.[web:3][web:13]
This page uses a default of 1680 kg/m³ for general gravel and allows you to change the value if your supplier specifies a different figure.[web:13]
Choosing depth and gravel size
For light-use borders or decorative spaces, a depth of 30–40mm is usually sufficient when using 10mm stones, as the smaller pieces pack closely together.[web:5][web:6]
For paths and driveways used by people or vehicles, UK guidance commonly moves towards 40–75mm, with 20mm gravel very widely used for driveways due to stability and drainage.[web:5][web:7][web:10]
Larger rounded pebbles or cobbles up to about 50–120mm often need 70–100mm depth so that the stones sit securely and do not roll across the surface.[web:5][web:10]
Typical UK gravel coverage examples
As a rough illustration, a square drive 5m by 5m covered to 40–50mm depth with 20mm gravel usually needs around three bulk bags, depending on the bag weight and exact stone density.[web:1][web:5][web:7]
A narrow path 10m long and 1m wide at 40mm depth could require around 0.4m³ of gravel, which is typically around 0.6–0.7 tonnes using a standard density figure.[web:3][web:13]
Always treat these as illustrations rather than precise quotes; delivery method, moisture content and stone type can all influence how much material you actually receive per bag.[web:3][web:13]
Step‑by‑step guide
- Measure the length and width of your area in metres or feet, or measure the diameter if it is roughly circular.[web:17][web:20]
- Decide on the project type and gravel size you prefer, then check the suggested depth range in the reference table above.[web:5][web:6][web:7]
- Enter your dimensions, chosen depth and application in the calculator, including a small allowance for wastage and settlement.[web:1][web:7][web:15]
- Review the output in square metres, cubic metres, tonnes and bag counts, and round up to a whole number of bags to avoid running short.[web:3][web:10][web:13]
- Confirm the bulk bag weight and gravel density with your aggregate supplier so that the quantities are in line with the specific product you intend to buy.[web:1][web:5][web:16]
Common questions about gravel for UK projects
How much gravel does 1 tonne cover?
Coverage from one tonne depends on both stone size and depth. For a general driveway gravel at 50mm depth, one tonne often covers somewhere around 12–15 square metres; a thinner decorative layer may cover more area, while a deeper base or very large cobbles will cover less.[web:4][web:8][web:11][web:14]
Is 20mm gravel better than 10mm for a driveway?
Many UK suppliers suggest 20mm gravel for driveways because it locks together more firmly and is less likely to migrate than 10mm stones, which can be pushed aside more easily and sometimes stick in tyre treads.[web:5][web:7][web:10]
Do I need an extra allowance for wastage?
It is normal to add around 5–15% on top of the calculated quantity to cover measuring inaccuracies, uneven ground and minor spillages, especially on larger jobs or where edging makes it hard to reuse surplus material elsewhere.[web:1][web:9][web:18]
Why does density matter when ordering gravel?
Different aggregates have different bulk densities, so two bulk bags with the same nominal weight can occupy slightly different volumes; knowing the approximate density helps you convert between cubic metres and tonnes more reliably.[web:3][web:13][web:19]
Can I reuse this method for sand or sub‑base?
The same volume approach works for sand, MOT Type 1 and other aggregates, but you should check the depth requirements and bulk density figures for those materials, as they often differ from decorative or driveway gravel.[web:3][web:8][web:12]
Typical mistakes when working out gravel
- Using the wrong depth for the project, such as laying driveway gravel at only 20–30mm, which often leads to bare patches and exposed membrane.[web:5][web:6][web:7]
- Mixing units, for example measuring length and width in metres but entering a depth in inches without converting it to millimetres or metres first.[web:3][web:9]
- Forgetting that edging, curves and slopes increase the actual area slightly compared with a simple rectangle drawn on paper.[web:17][web:20]
- Relying on bag counts stated for a different gravel density than the product being purchased, which can cause noticeable shortages on site.[web:3][web:13][web:18]
- Not allowing any extra material for topping up after the first season, when gravel can settle and compact under regular traffic.[web:1][web:7][web:10]
References
Gravelmaster. Gravel calculator and driveway gravel guidance. Gravelmaster website, accessed 2025.[web:1][web:17]
Decorative Aggregates. Calculate your gravel needs and depth recommendations for UK projects. Decorative Aggregates website, accessed 2025.[web:5]
JT Atkinson. Gravel calculator FAQs and depth suggestions for paths and driveways. JT Atkinson website, accessed 2025.[web:7][web:16]
Calculator.net and GIGACalculator.com. Gravel calculators explaining volume, depth and density conversions between cubic metres and tonnes.[web:3][web:13]
Stone Warehouse and Gravel Shed. UK decorative aggregate laying depth guides for gravel, chippings, pebbles and cobbles.[web:6][web:10]
Additional coverage and depth examples from UK and international aggregate suppliers and construction guides.[web:4][web:8][web:9][web:11][web:12][web:14][web:15][web:18][web:19][web:20]