Overview
Because the stones roll, pea gravel suits foot traffic on firm edging, not vehicle turning areas.
How the calculation works
Pea gravel weight = area × depth × 1.6 t/m³ — 0.08 tonnes per square metre at the usual 50mm depth.
One 850kg bulk bag holds about 0.53 m³, covering 10.6 m² at 50mm or 13.3 m² at 40mm.
Drainage surrounds are calculated the same way: trench length × width × gravel depth around the pipe.
Worked example
A side path 12m × 0.8m dressed with pea gravel at 50mm.
Area = 9.6 m². Volume = 0.48 m³. Weight = 0.48 × 1.6 = 0.77 tonnes.
Order one 850kg bulk bag with allowance included, or 35 × 25kg bags.
10mm pea shingle at a glance
- Planning density1.60 t/m³
- Typical range1.40–1.70 t/m³
- CategoryGravel
- CompactionUsually not applied
- SourcePlanning value based on typical UK 10mm shingle bulk densities
- Reviewed2026-08-16
Planning values for typical UK supplies; your supplier product data takes precedence.
10mm pea shingle coverage guide
| Depth | Area per tonne | Area per 850kg bag | Weight per m² |
|---|---|---|---|
| 25mm | 25.0 m² | 21.3 m² | 40 kg |
| 40mm | 15.6 m² | 13.3 m² | 64 kg |
| 50mm | 12.5 m² | 10.6 m² | 80 kg |
| 75mm | 8.3 m² | 7.1 m² | 120 kg |
| 100mm | 6.3 m² | 5.3 m² | 160 kg |
| 150mm | 4.2 m² | 3.5 m² | 240 kg |
Computed from a 1.60 t/m³ planning density on level ground.
Assumptions and accuracy
1.6 t/m³ is a planning value for washed 4-10mm pea shingle; coloured and imported products vary.
Pea gravel migrates without firm edges and a membrane; the quantity does not change but the finish does.
Play-area depths are a safety decision — follow the surface system manufacturer's requirements.
How to use this calculator
- Measure the path or border, including any edging strips.
- Enter 50mm for foot-traffic finishes; use the trench dimensions for drainage surround.
- Pea shingle 10mm is preselected; switch to 20mm gravel for vehicle areas.
- Check bulk bag weights — 850kg is common but not universal.
When pea gravel is commonly used
Pea gravel finishes garden paths, borders and courtyards, surrounds land drains and perforated pipe, and tops pots and planters. Grey, beige and black pea gravels are colour variants of the same grading.
Frequently asked questions
How much pea gravel do I need?
At 50mm deep allow 80kg per square metre. A 10 m² area needs about 0.8 tonnes — one 850kg bulk bag — before any extra for settlement.
How many m² does a bulk bag of pea gravel cover?
About 10.6 m² at 50mm or 13.3 m² at 40mm, assuming an 850kg bag and 1.6 t/m³ planning density.
Is pea gravel good for driveways?
Only for light, straight runs with firm edging — the rounded stones roll and scatter under turning wheels. 20mm angular gravel over a Type 1 sub-base is the usual driveway choice.
How deep should pea gravel be in a play area?
Fall-height protection is a safety specification set by the surface system manufacturer — never inferred from a general calculator. Follow their required depth and certification for the equipment in question.
References and source notes
- Typical UK 10mm pea shingle bulk density from supplier technical data (planning value).