Gravel Calculator

How Much Gravel Do I Need?

This free gravel calculator works out exactly how much gravel, pea shingle or decorative stone you need for any project — driveways, garden paths, borders, play areas and drainage. Enter your dimensions in metres or feet, set the depth in centimetres or inches, choose your gravel type, and get an instant answer in cubic metres, tonnes, bulk bags and 25kg bags.

The calculator uses a simple formula — length × width × depth — to find the volume, then multiplies by the density of your chosen gravel type to convert into weight. This matters because gravel in the UK is sold by weight (tonnes or kilograms), not by volume. Different types of gravel have different densities: MOT Type 1 is much heavier at 2,100 kg/m³, while decorative aggregate is lighter at 1,400 kg/m³. Getting the density right means you order the correct amount and avoid costly extra deliveries.

Planning a landscaping project? Our mulch calculator works out bark and wood chip quantities, and the soil calculator handles topsoil and compost for raised beds and borders.

Gravel Driveway Calculator — How Much Do You Need?

Driveways need more gravel than garden paths because vehicles compact the surface. A gravel driveway also requires a compacted sub-base underneath. Here is how to calculate quantities for common UK driveway sizes.

Driveway Gravel Quantities

Important: These quantities are for the gravel surface layer only. Driveways also need a 100–150mm compacted MOT Type 1 sub-base underneath. For a single-car driveway (3m × 6m), that adds another 1.8–2.7m³ of hardcore.

Use 20mm angular gravel for driveways — not pea gravel. Angular stones interlock under vehicle weight and stay in place. Pea gravel is rounded and will scatter into the road. Golden gravel, Cotswold stone or recycled aggregate are all good driveway choices.

Gravel Sizes UK — Which Size for Which Job?

Gravel is sold by stone size in millimetres. The size you need depends entirely on what the gravel is for.

Rule of thumb: The larger the stone, the deeper you need to lay it for stable coverage. Anything under 14mm needs edging to stop it migrating into lawns and borders.

Types of Gravel for UK Gardens

Choosing the right type of gravel makes a real difference to how your project looks and performs. I have used most of these in my own garden over the years, and each one has its strengths. Here is a breakdown of the main types available in the UK and when to use them.

10mm Pea Gravel

Pea gravel is one of the most versatile options for UK gardens. The small, rounded stones are comfortable underfoot and work brilliantly in play areas, around seating zones and as a decorative top-dressing for plant borders. Because the stones are rounded rather than angular, they do not compact well, which means they shift underfoot on sloping ground. I tend to use pea gravel for flat decorative areas and recommend angular stone for paths with any gradient. Density is around 1,600 kg/m³, so a cubic metre weighs 1.6 tonnes.

20mm Gravel and Shingle

This is the standard all-rounder and what most people mean when they say "gravel." The 20mm size strikes a good balance between being large enough not to get kicked everywhere and small enough to walk on comfortably. It is the go-to choice for garden paths, driveways with a proper sub-base, and general landscaping. A cubic metre weighs approximately 1,500 kg (1.5 tonnes). When buying for a driveway, always lay it over a compacted MOT Type 1 sub-base — without this, the gravel sinks into the soil within months.

Decorative Aggregate

This covers everything from golden flint to plum slate, rainbow stone and white marble chips. Decorative aggregates are lighter at around 1,400 kg/m³ and are chosen primarily for appearance rather than structural performance. I used Cotswold Gold aggregate for the borders around my front garden and it has held its colour well after two years, though I did top it up slightly after the first winter. Keep it to 3–5 cm depth over heavy-duty weed membrane for the best results.

MOT Type 1

MOT Type 1 is not really a garden gravel — it is a crushed limestone sub-base material used underneath driveways, patios and shed bases. It compacts down hard when vibrated with a plate compactor, creating a stable foundation. At 2,100 kg/m³ it is significantly heavier than decorative gravel. For a typical driveway, you need 100–150mm of compacted Type 1 beneath 50mm of decorative gravel on top. Our sub-base calculator can work out exactly how much you need for the foundation layer.

Slate Chippings

Welsh slate chippings in 20mm or 40mm sizes give a contemporary, modern look to garden borders and paths. The dark blue-grey colour contrasts beautifully with green planting and light-coloured walls. They do not break down over time like organic mulches, so they are a long-term solution — I have some 40mm slate around my raised beds that has been there for four years with no sign of deterioration. Density is similar to standard gravel at around 1,500 kg/m³.

How to Lay Gravel — Step by Step

Getting the preparation right is the difference between gravel that looks great for years and gravel that becomes a weedy, uneven mess within six months. I have laid gravel on three separate areas in my own garden, and the one I skimped on preparation for is the one I ended up redoing. Here is the method that works.

Step 1: Mark Out and Excavate

Use string lines and pegs to mark your area. For a decorative border, excavate 75–100mm deep. For a driveway, you need to dig down 200–250mm to allow room for sub-base and gravel. Remove all vegetation, roots and loose soil. If the ground is soft clay, excavate an extra 50mm and add geotextile fabric before the sub-base.

Step 2: Install Edging

Without edging, gravel migrates into lawns and borders within weeks. I use aluminium lawn edging for curved borders and treated timber boards for straight runs. Metal edging costs around £3–£5 per metre and lasts indefinitely. Secure it with steel pins every 500mm. For driveways, use kerb stones or block paving edging set in concrete for a permanent edge.

Step 3: Lay Weed Membrane

Lay heavy-duty landscape fabric over the entire area, overlapping sheets by at least 150mm. Use membrane pins to hold it in place. Cheap, thin membrane is a false economy — it tears within a year and weeds push straight through. Spend the extra on 100gsm or heavier woven geotextile. For driveways, skip the membrane over the sub-base layer — it goes between the sub-base and the decorative gravel on top.

Step 4: Compact the Sub-Base (Driveways Only)

For driveways and areas with vehicle traffic, spread 100–150mm of MOT Type 1 and compact it with a vibrating plate compactor. You can hire a plate compactor from most tool hire shops for around £30–£40 per day. Compact in 50mm layers for the best result. The sub-base should be firm enough that you can walk on it without leaving footprints.

Step 5: Spread and Level the Gravel

Tip your gravel onto the membrane (or sub-base for driveways) and spread it with a landscaping rake. Work in sections, checking depth with a ruler or offcut of timber marked at the right depth. For paths and borders, 30–50mm is the standard depth. For driveways, 40–50mm of decorative gravel over the sub-base. Rake it level and use a spirit level on a straight edge to check for any dips.

Step 6: Consider Gravel Grid Panels

For driveways and parking areas, gravel grid panels stop the stones from shifting under tyres. These are interlocking plastic honeycomb panels that sit on the sub-base, filled with gravel. They add around £8–£12 per square metre to the cost but make a massive difference to how stable the surface feels. They also reduce the amount of gravel you need by keeping it contained rather than being pushed to the edges.

How Much Does Gravel Cost in the UK?

Gravel prices vary enormously depending on the type, quantity and how you buy it. Here is what I have found from pricing up projects across several UK suppliers in 2026.

Buying in 25kg Bags

Individual 25kg bags from B&Q, Wickes or Amazon typically cost £4–£8 each depending on the type. That works out at £160–£320 per tonne — expensive for anything more than a small border. A bag covers approximately 0.5 square metres at 30mm depth with 20mm gravel. For a 10 square metre path at 50mm depth, you would need around 30 bags (750 kg), costing £120–£240. Only buy bags for small projects or top-ups.

Buying Bulk Bags (850kg–1,000kg)

Bulk bags, also called dumpy bags or tonne bags, are the sweet spot for medium-sized projects. A standard bulk bag contains 850–1,000 kg and costs £40–£100 delivered, depending on your area and the gravel type. That is roughly half the price per tonne compared to 25kg bags. One bulk bag covers approximately 10 square metres at 50mm depth with 20mm gravel.

Loose Delivery by the Tonne

For larger projects like driveways (typically 2–5 tonnes), loose delivery from a local aggregate supplier is the cheapest option. Expect to pay £25–£55 per tonne for standard gravel, plus a delivery charge of £30–£80 depending on distance. A 3m × 6m single-car driveway at 50mm depth needs around 1.35 tonnes of gravel plus 2.7 tonnes of MOT Type 1 sub-base — a total material cost of roughly £120–£200 delivered.

Prices are estimates based on standard 20mm gravel in 2026. Decorative aggregates like slate chippings cost 2–3 times more. Always get at least two quotes from local suppliers — prices vary significantly by region, with Scotland and the North West typically cheaper than the South East due to proximity to quarries.

Common Gravel Mistakes to Avoid

I see the same mistakes repeated on gardening forums every spring. Here are the ones that cost the most time and money to fix.

Skipping the Weed Membrane

Without a proper weed membrane underneath, weeds will push through gravel within 3–6 months. I made this mistake on my first gravel border and spent an entire summer pulling out couch grass and dandelions. Ripping it all up, laying membrane and re-gravelling cost me twice as much as doing it properly the first time. Budget £1–£2 per square metre for quality 100gsm woven membrane.

Not Adding Edging

Gravel without a physical edge migrates everywhere — into the lawn, onto paths, into borders. Within a year you will have a thin, patchy surface and gravel where you do not want it. Metal edging, timber boards or stone kerbs all work. The cost is typically £3–£8 per linear metre and saves you from buying replacement gravel every year.

Laying Gravel Directly on Clay Soil

Heavy clay soil swallows gravel. The stones sink into the wet clay over winter, and by spring you are walking on mud with a few stones mixed in. Always lay geotextile fabric on clay soil before adding sub-base or gravel. For driveways on clay, a deeper sub-base of 200mm rather than the standard 150mm makes a real difference.

Ordering Too Little

The most common mistake is underestimating how much gravel you need. Gravel compresses slightly when walked on, and irregular ground shapes use more than you expect. I always add 10% to my calculated amount for paths and borders, and 15% for driveways. The cost of a small top-up delivery is disproportionately expensive — it is always cheaper to order slightly more than you think you need.

Choosing the Wrong Size for Driveways

Small pea gravel (10mm and under) looks beautiful but is impractical for driveways. It gets stuck in tyre treads, kicks up when cars drive over it, and does not compact well. Use 20mm angular gravel for driveways — it locks together under weight and stays put. Save the pea gravel for decorative areas where vehicles will not go.

Gravel Maintenance — Keeping It Looking Good

One of the biggest advantages of gravel over other surfaces is how little maintenance it needs. But "low maintenance" does not mean "no maintenance." Here is what I do to keep my gravel areas looking fresh.

Raking and Levelling

After a few months, foot traffic and rain create dips and uneven patches in gravel paths and borders. A quick rake with a landscape rake once a month keeps everything level and looking tidy. For driveways, rake any tyre tracks smooth every few weeks. This takes 10–15 minutes for a typical path and makes a surprising difference to the overall appearance.

Weed Control

Even with weed membrane, some weeds will appear — usually in the gravel itself from wind-blown seeds settling in the gaps between stones. These surface weeds pull out easily by hand because they have no deep roots. A quick pass with a hoe or hand-weeding every couple of weeks keeps on top of them. Avoid weedkiller sprays on decorative gravel as they can stain lighter-coloured stones.

Topping Up

Gravel slowly thins over time as stones get kicked to the edges, compacted into the ground or carried away on shoes. Plan to top up your gravel every 2–3 years. A 10 square metre path typically needs 2–3 bags (50–75 kg) of top-up material. Keep a spare bag in the shed so you can fill any thin spots as they appear rather than waiting until the membrane shows through.

Leaf and Debris Removal

Autumn leaves left on gravel trap moisture, stain light-coloured stones and rot down into a layer of organic matter that weeds love. Use a leaf blower on a low setting or a spring-tine rake to clear leaves regularly through autumn. Avoid using a standard garden rake as it drags the gravel with the leaves.

Recommended Gravel Depths by Project

Getting the depth right is critical — too shallow and you see membrane through the gravel, too deep and you waste money. Here are the recommended depths for common UK garden projects based on industry standards and my own experience.

Frequently Asked Questions

Best Gravel & Decorative Stone UK 2026 — Our Top Picks

These are the most popular gravel and decorative stone products available in the UK right now — from budget pea shingle to premium slate chippings.

Links above are affiliate links — we may earn a small commission at no extra cost to you.

Where to Buy Gravel in the UK

Once you know how much gravel you need, compare prices across these suppliers. For large quantities (1 tonne+), bulk bags or loose delivery are significantly cheaper per tonne than 25kg bags.

Links marked above are affiliate links — we may earn a small commission at no extra cost to you. We only link to reputable UK suppliers.