TradeCalculator.co.uk
Artificial Grass Calculator — How Much Fake Grass Do I Need?
Calculate artificial grass, sub-base, sand, membrane and fixings for your garden. UK roll sizes and materials.
Longest dimension of your area
Shortest dimension
Adds 10% for trimming and fitting
10% is standard for rectangular areas
Heavy-duty landscape membrane
50mm compacted MOT sub-base
15mm levelling layer
Price of artificial grass per m²
Compacted Type 1 MOT depth — 50mm min for domestic, 75–100mm for driveways/heavy use
Sharp sand or grano laying course (typically 15–25mm)
Compacted Type 1 ≈2,100 kg/m³ (range 2,000–2,200). Material is bought loose — allow a 5–10% margin for compaction
U-pin spacing around perimeter — a trade convention (commonly 100–300mm), default 200mm
Next up: related pages
How We Calculate This
Our artificial grass calculator works out all the materials you need for a complete installation, including the grass itself, sub-base preparation, weed membrane, and fixings.
The formula
Grass area = Length × Width × Wastage factor
Sub-base (kg) = Area × 0.05m depth × 2,100 kg/m³ (compacted Type 1)
Sharp sand (kg) = Area × 0.015m depth × 1,600 kg/m³
Edging pins = Perimeter ÷ 0.2m spacing
Installation layers
- Sub-base: 50mm minimum compacted Type 1 MOT (≈2.1 tonnes per m³). Bought loose and compacts ~10–15%, so allow a 5–10% margin.
- Levelling layer: 15–25mm sharp sand or granite/limestone dust (≈1.6 tonnes per m³)
- Weed membrane: 100g/m² minimum non-woven, 150–200mm overlaps (calculator allows 10% over grass area)
- Artificial grass: Available in 2m and 4m wide rolls
- Edging pins: Galvanised U-pins, typically every 100–300mm around the perimeter (default 200mm — a trade convention, not a regulated value)
Sub-base depth, density and pin spacing are aggregate-supplier and installer conventions rather than figures set by a British Standard. The Type 1 density (2.0–2.2 t/m³, 2.1 t/m³ working estimate) follows UK aggregate-supplier guidance (Armstrongs Group; Soils & Stone, SHW Series 800 Clause 803). Joining tape is estimated for side-by-side strip seams only — add the extra seam length if your area is longer than the supplied roll and rolls must be butted end-to-end.
Frequently Asked Questions
Measure your area in metres (length x width), then add 10% for wastage and trimming. Artificial grass comes in 2m or 4m wide rolls, so you may need multiple strips joined together. Always lay rolls in the same direction so the pile faces the same way.
You need a 50mm compacted layer of Type 1 MOT sub-base (crushed limestone/granite), followed by a 15-25mm laying course of sharp sand or granite/limestone dust (‘grano’) to level the surface. At a compacted density of about 2.1 tonnes/m³, every 10 m² at 50mm needs roughly 1,050kg (≈1.05 tonnes) of Type 1 — order a 5–10% margin as it is supplied loose and compacts ~10–15%. Use our Type 1 Sub-Base Calculator to work out exact quantities for your area.
Yes, always install a heavy-duty weed membrane between the sub-base and the grass. A permeable non-woven landscape fabric (100g/m² minimum) prevents weed growth through the drainage holes. Overlap joins by 150–200mm (suppliers typically recommend 200mm); this calculator adds 10% over the grass area to cover overlaps and trimming. Use our Weed Membrane Calculator for quantities.
Quality artificial grass typically lasts 15-20 years with proper installation and minimal maintenance. Premium products with UV stabilisation will retain colour better. Budget options may fade or flatten after 8-10 years. Brushing the pile occasionally helps maintain appearance.
Use specialist artificial grass joining tape and adhesive. Lay the tape adhesive-side up along the join line, fold back both edges of grass, apply adhesive to the tape, then press both edges down onto the tape. Ensure the pile direction matches on both strips. Allow 24 hours for adhesive to cure.
Related Calculators
Was this calculator helpful?
Last updated: February 2026
Verified against UK standards · estimates only, confirm with your supplier.