Gravel Calculator
Find how many tonnes and bulk bags of gravel you need for a drive, path or border.
Measure your project
Your answer
That is 1.00 m³.
If you buy bags
If you buy bulk bags
Wickes gives its gravel cover at 25 mm deep. For a drive, check your local building rules or ask a builder or engineer.
What it costs
Our £75 bulk bag price (with VAT) comes from only 3 UK sellers, Oct 2026. Treat it as a rough guide.
Quick answers
- A 5 × 4 m area, 50 mm deep
- About 1.60 tonnes, or 2 bulk bags of 800 kg.
- Weight of 1 m³
- About 1.6 tonnes, from Wickes's cover figure for 20 mm gravel.
- What one bulk bag covers
- An 800 kg bag covers about 20 m² at 25 mm, or 10 m² at 50 mm.
- Small bags
- A Wickes Major Bag holds 22.5 kg. About 36 of them weigh the same as one 800 kg bulk bag.
How to work it out
- Tape the length and width of your drive, path or border in metres. Multiply them for m².
- Decide how deep the gravel will sit, in mm. Divide that by 1,000.
- m² × depth in metres = m³ of gravel.
- Gravel is about 1.6 tonnes per m³, so m³ × 1.6 = tonnes.
- Tonnes ÷ 0.8 = bulk bags of 800 kg. Round any part bag up.
5 × 4 × 0.05 = 1 m³
1 × 1.6 = 1.60 tonnes
1.60 ÷ 0.8 = 2 → 2 bags
Gravel for common sizes
Pick the row nearest your area. Each depth has its own tonnes and bags.
| Size | Tonnes, 25 mm | Bags | Tonnes, 50 mm | Bags |
|---|---|---|---|---|
| 5 × 1 m | 0.20 | 1 | 0.40 | 1 |
| 3 × 3 m | 0.36 | 1 | 0.72 | 1 |
| 4 × 4 m | 0.64 | 1 | 1.28 | 2 |
| 5 × 4 m | 0.80 | 1 | 1.60 | 2 |
| 10 × 3 m | 1.20 | 2 | 2.40 | 3 |
| 10 × 5 m | 2.00 | 3 | 4.00 | 5 |
Exact sizes with nothing extra. A part bag is shown as a whole one.
What a tonne or a bag covers
Wickes says its 800 kg bag of 20 mm gravel covers 20 m² at 25 mm. So a cubic metre weighs about 1.6 tonnes. We use that weight for every sum on this page.
| Depth | 1 tonne | 800 kg bag | 22.5 kg bag |
|---|---|---|---|
| 25 mm | 25 m² | 20 m² | 0.56 m² |
| 40 mm | 15.6 m² | 12.5 m² | 0.35 m² |
| 50 mm | 12.5 m² | 10 m² | 0.28 m² |
| 75 mm | 8.3 m² | 6.7 m² | 0.19 m² |
How deep should gravel be?
We found no UK guide that sets a depth for gravel, so we don't give one. Wickes quotes its gravel cover at 25 mm. It quotes its slate cover at 50 mm.
For a drive, check your local building rules or ask a builder or engineer.
Small bags, bulk bags and price
Tonnes, m³ and bags
To turn m³ into tonnes, multiply by 1.6. To turn tonnes into m³, divide by 1.6.
So 1 m³ of gravel weighs about 1.6 tonnes. That fills 2 bulk bags of 800 kg, or 72 Major Bags.
Bags and price
Wickes sells gravel in small Major Bags of 22.5 kg. One 800 kg bulk bag weighs as much as about 36 small bags.
A bulk bag from Wickes is 800 kg; from Tippers, it is 850 kg or more. So one seller's bag can hold more gravel than another's.
Bulk bag prices for 20 mm gravel, with VAT, from Wickes, Tippers and Lawsons:
- Lowest: £54
- Middle: £75 (the calculator uses this)
- Highest: £79.91
With only 3 sellers, treat the middle price as a rough guide. Ask a local builders' merchant, with delivery.
We have no checked price for small bags, so the calculator prices bulk bags only.
Slate chippings
Slate chippings weigh about the same as gravel. Wickes says its 800 kg bag of slate covers 10 m² at 50 mm. That is 1.6 tonnes per m³, so this calculator works for slate too.
Slate costs more. Our slate price is £136.88 a bulk bag, with VAT. That is the middle of 3 prices from only 2 sellers, so treat it as a rough guide. The lowest was £129.14 and the highest £175.
| Size | 800 kg bags | Gravel | Slate |
|---|---|---|---|
| 3 × 3 m | 1 | £75 | £136.88 |
| 5 × 4 m | 2 | £150 | £273.76 |
| 10 × 3 m | 3 | £225 | £410.64 |
Our middle bag prices, with VAT. Delivery not added.
Questions people ask
How much gravel do I need?
Find the m³ first: length × width × depth, in metres. Then m³ × 1.6 gives tonnes. A 5 × 4 m border at 50 mm takes about 1.6 tonnes.
How much gravel do I need per square metre?
About 40 kg for each m² at 25 mm deep, or 80 kg at 50 mm.
How many square metres does a tonne of gravel cover?
About 12.5 m² at 50 mm deep, and 25 m² at 25 mm.
How much gravel is a tonne?
A tonne of gravel fills about 0.63 m³. That is a cube about 85 cm on each side.
How much gravel is in a bulk bag?
About 0.5 m³ in a Wickes 800 kg bag. Tippers fills its bags with at least 850 kg.
How much does a bulk bag of gravel cover?
Wickes says 800 kg covers 20 m² at 25 mm deep. At 50 mm, that is about 10 m².
How many bags of gravel do I need?
Work out the tonnes, then divide by the bag weight. One m² at 50 mm takes 4 Major Bags of 22.5 kg. A 5 × 4 m area takes 72 of them, or 2 bulk bags.
How much is a bulk bag of gravel?
About £75 with VAT, in October 2026. It is the middle of only 3 UK sellers, so treat it as a rough guide.
Where our numbers come from
- Gravel weight: Wickes 20 mm gravel bulk bag (800 kg covers 20 m² at 25 mm)
- Small bags: Wickes Major Bags (20 kg sand, 22.5 kg gravel)
- 850 kg bulk bags: Tippers aggregates list
- Bulk bag prices: the middle price from 3 UK sellers each (Wickes, Tippers, Lawsons; Oct 2026)
- Slate weight: Wickes 20 mm slate chippings bulk bag
- Slate chippings price: the middle of 3 prices from only 2 UK sellers (Wickes, Tippers; Oct 2026, with VAT)
Made by BuildersCount. Last checked 3 Oct 2026.
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