How much gravel or bark?
Updated
Ordering too little means a second delivery charge; ordering too much leaves a bag on the drive. A short sum gets you close.
1. Measure the area
Multiply the length by the width, in metres, to get the area in square metres. For an awkward shape, split it into rectangles and add them up.
2. Choose a depth
| Where | Gravel or chippings | Bark or mulch |
|---|---|---|
| Borders and beds | 30 to 40mm | 50 to 75mm |
| Paths and patios | 40 to 50mm | For a path, coarse wood chip: 75mm, or 100mm where it's walked daily, with edging |
| Drives | 40 to 50mm of angular 14mm or 20mm gravel, not rounded pebbles, over a compacted sub-base, typically 100 to 150mm of MOT Type 1 | Not suitable |
These are rough guides. Larger stones need a deeper layer to cover the ground; smaller ones spread further.
3. Do the sum
Gravel and chippings (sold by weight)
area (m²) × depth (m) × 1.6 = tonnes
Stone weighs roughly 1.4 to 1.7 tonnes a cubic metre, depending on the type. A figure of 1.6 suits most decorative gravel; heavier stone such as basalt is nearer 1.7, so use the supplier's own figure if it gives one. For a path 10 metres long and 1 metre wide at 50mm deep: 10 × 0.05 × 1.6 = 0.8 tonnes.
Bark and mulch (sold by volume)
area (m²) × depth (m) × 1,000 = litres
For a 12 square metre border at 75mm deep: 12 × 0.075 × 1,000 = 900 litres.
How far a bulk bag goes
Bulk bags of stone are sold by weight, often 800 to 850kg. At 50mm deep, a bag covers roughly 10 square metres; at 30mm, about 17. A bulk bag of bark is often a cubic metre (1,000 litres), but check the listing. A cubic metre covers about 20 square metres at 50mm, or 13 at 75mm.
Before it arrives
- Lay a weed membrane under gravel. It keeps most weeds down and stops the stones sinking into the soil.
- Edge paths and borders, so the gravel stays where you put it.
- Bulk bags usually come by lorry and are left at the kerbside or on the drive. Make sure there's room, and check whether the lorry can reach.
- Add 10% to allow for settling, or 15% on uneven ground. A little left over is useful for topping up.
Please note: this guide is general advice to help you choose, not professional or legal advice. Every garden and every product is different, so always follow the maker's instructions and check with your council or a qualified tradesperson if you're unsure.
Sources
- Travis Perkins: Gravel and shingle bulk bag, 20mm
- Gravelmaster: Gravel calculator; How to lay a gravel driveway; Delivery
- Marshalls: What sub-base do I need?
- Material Calculator: Gravel calculator
- Gravelbase: Gravel calculator
- RHS: Mulch; Woody waste: using as mulch
- Outdoor Aggregates: How to lay bark; Wood chip path; Membrane under gravel
- Stone Warehouse: How to lay a gravel driveway
- Decorative Aggregates: How to create and maintain a gravel garden; Delivery
- Mainland Aggregates: Delivery information
See also: getting it to your garden.