GardenCalcs.uk
Artificial Grass Calculator — Materials & Cost Estimate
Calculate how much artificial grass, sub-base, weed membrane, and infill sand you need.
Longest run of the lawn area; rolls are laid along this dimension
Width across the area; determines how many roll strips and joins you need
Budget lasts ~8-10 yrs; premium ~15-20 yrs and feels softer
Soil and lawn need a Type 1 sub-base; concrete/paving can be laid directly
Standard UK rolls are 2m or 4m wide; wider rolls mean fewer joins
10% suits simple rectangles; raise to 15-20% for awkward or multi-cut shapes
50mm Type 1 for patios/light use; 75-100mm for heavy or soft-ground use
2-4 kg/m² kiln-dried silica sand; use more for longer pile heights
How We Calculate This
How The Calculations Work
- Grass area: Length × Width, plus a wastage allowance (default 10%) for trimming and cutting
- Sub-base: Area × depth (mm) ÷ 1000 × 1.7 — using an indicative MOT Type 1 density of ~1.7 t/m³ (loose ~1.5, compacted ~2.0); treat the tonnage as an estimate and round up when ordering
- Weed membrane: Same area as the grass (including wastage)
- Joining tape: Strips = ⌈shorter side ÷ roll width⌉; joins = strips − 1; tape = joins × longer side. A 4m-wide area on 4m rolls needs no join; a 2m roll choice joins more often
- Infill sand: Area × kg per m² of kiln-dried silica sand (typically 2-4 kg/m²)
Frequently Asked Questions
Measure your area (length × width) and add about 10% for cutting waste and trimming. Artificial grass is sold in 2m and 4m wide rolls (typically up to 25m long), so plan your strips to run along the longest dimension and minimise joins. Always lay every strip with the pile leaning the same way for a consistent, seamless look.
On soil, you need to remove the top 50-75mm and replace with compacted Type 1 aggregate (MOT). On concrete or paving, you can lay directly with a shock pad for comfort. The sub-base should be level and well-compacted with a slight drainage fall.
Kiln-dried silica sand infill (typically 2-4 kg per m², depending on pile height and density per NeoGrass guidance) helps weigh down the grass, keeps the blades upright, and improves drainage and fire resistance. Most quality lawn turfs benefit from it. Brush it down into the pile with a stiff broom after laying so the sand sits at the base and is not visible.
Budget grass costs £6-£10/m², mid-range £12-£20/m², and premium £22-£35/m². Installation typically adds £15-£30/m² including sub-base preparation. Higher quality grass looks more natural, feels softer, and lasts longer (15-20 years vs 8-10 for budget).
Yes, always lay weed membrane on top of the sub-base before the grass. This prevents weeds growing through. Use a heavy-duty geotextile membrane, not basic landscape fabric. On concrete, membrane is not needed.
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Last updated: March 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.