#1 Gravel Calculator

To calculate the weight needed to cover your specific area, such as pathways or driveways with our gravel or pebbles, you will need to know the length, width and depth of your space. By calculating the size of your outdoor space, our calculator will let you find an estimate which will help you while completing the order.

Our calculator converts your length × width × depth into cubic metres, then multiplies by the density of the stone (about 1,600 kg/m³ for gravel and 1,800 kg/m³ for smooth pebbles) to give you a weight in kilograms and a bag count.

As a rule of thumb, 1 m² of gravel needs roughly 80 kg at 50 mm depth, which is about four to five 20 kg bags. At a shallower 25 mm, one bag covers half a square metre.

• 25 mm depth ≈ 40 kg of gravel / 45 kg of pebbles per m²
• 40 mm depth ≈ 64 kg / 72 kg per m²
• 50 mm depth ≈ 80 kg / 90 kg per m²
• 75 mm depth ≈ 120 kg / 135 kg per m²
• 100 mm depth ≈ 160 kg / 180 kg per m²

Smooth pebbles pack a little more tightly than angular gravel, so they weigh roughly 10–12% more per square metre. At a typical 50 mm depth you will need about 90 kg of pebbles per m², or around four to five of our 20 kg hand-packed bags.

The depth of gravel depends on the purpose for which it is being used. For general landscaping purposes, such as creating a driveway or walkway, a depth of 50mm (2 inches) is typically sufficient. For decorative purposes, a shallower depth of 25-50mm (1-2 inches) may be used.

Use 25 mm around pots and borders, 40 mm for walking paths, 75 mm for driveways, and 100 mm for ground-cover or weed suppression.

As heavy as it may sound, 20 kilograms or 50 pounds is not a lot when we look at the area we want to decorate in meters squared. Therefore, it is essential to understand the weight factor. For example, 20 kilograms of pebbles may cover only 0.5m² at 25 mm deep, and please do remember it does vary on the depth of the gravel or aggregate used. Do not feel discouraged — the final results are excellent.

The coverage of a ton of gravel depends on the size of the pebbles and the desired depth of the coverage. On average, a ton of 20 mm gravel will cover approximately 10 square metres to a depth of 50 mm, while a ton of 40 mm gravel will cover approximately 5 square metres to a depth of 50 mm. These are rough estimates and the actual coverage may vary based on factors such as the levelness of the surface and how tightly the stones are packed. It is always recommended to overestimate the amount needed to ensure you have enough for your project.

Yes — our calculator is built with all our products in mind. Pick the stone type (pebbles or gravel) and the right depth preset, and the numbers adjust automatically. For cobbles and very large pebbles you typically lay a single layer rather than filling to a depth, so divide the target area by the footprint of a single stone for the count.

For example, if you want to cover 1 m² (1 metre × 1 metre) of your area to a depth of 50 mm, you will need approximately 100 kg of pebbles or gravel. On the other hand, a depth of 30 mm will need around 60 kilograms. We recommend a depth of at least 50 mm for most garden projects — anything shallower tends to shift and expose the ground beneath.

Yes — our gravel calculator is 100% free, with no sign-up, no email wall, and no limits. Use it as many times as you like for any garden project. It runs entirely in your browser, so your measurements stay on your device.

We use industry-standard bulk densities — 1,600 kg/m³ for most garden gravel and 1,800 kg/m³ for tumbled pebbles — which are accurate for the overwhelming majority of UK decorative aggregates. The estimator rounds bag counts up to the nearest whole bag.

Real-world coverage varies with how tightly you pack the stones, the levelness of the ground beneath, and moisture content. For that reason we always suggest ordering one or two extra bags — it's much easier than running short on the day.

Gravel typically means angular, crushed stone between 2 mm and 40 mm — the classic driveway and path material. Pebbles are naturally rounded or tumbled stones, usually 10–60 mm, prized for decorative use. Cobbles are the largest category, typically 60–120 mm, used one-layer deep for features, pond edges and dry river beds.

Our calculator handles all three — the main thing that changes between them is the density (weight per cubic metre) and the depth you should lay them at.

For almost every garden project, yes. A permeable landscape fabric under your gravel does three things: it stops weeds pushing through, it prevents stones gradually sinking into the soil, and it keeps the colour of your pebbles clean by stopping mud splash-up. Budget roughly the same area of membrane as your gravel area, plus 10% for overlaps.

At Stones4Gardens, we do not offer bulk bags of gravel — we believe in providing our customers with the best quality pebbles and gravel. Each 20 kg bag of our product is hand-picked by our team to ensure that you receive only the highest quality stones. We understand the importance of having top-notch materials for your garden projects and strive to provide our customers with the best possible experience. By selecting each bag by hand, we ensure that every bag meets our standards and that our customers receive the best possible product. Please contact us for further information or to place an order for our high-quality, hand-selected pebbles and gravel.

Spring and early summer (April–June) are peak season for a good reason — the ground is firm, the weather is drier, and stone colours show their best when dry. Autumn is also excellent if you lay a weed membrane first. Try to avoid frozen or waterlogged ground, as it makes levelling and compacting much harder.

Unopened, undamaged bags can be returned in line with our refund policy. If you're unsure about quantities, always round up slightly using our calculator — it's far easier and cheaper than running short mid-project and waiting for a second delivery.