Artificial grass calculator: roll layout and seams
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Lawn length | 6 m |
| Lawn width | 5 m |
| Roll widths you can buy | 2, 4 m |
| Which way should the pile run? | Whichever buys least |
| Extra length per strip for trimming | 0 mm |
| Sharp sand density | 1.6 t/m³ |
Order: 30.00 m² of grass (2 pieces, 1 seam)
| Result | Value |
|---|---|
| Grass to buy | 30 m² |
| Lawn area (fitted) | 30 m² |
| Offcut | 0 m² |
| Seams | 1 |
| Seam length | 5 m |
| Weed membrane (the lawn area) | 30 m² |
Pieces to cut
- Piece 1: 4 m wide × 5 m long
- Piece 2: 2 m wide × 5 m long
Show the working
- Lawn: 6 × 5 m = 30 m²
- Pile runs along the width: strips 5 m long cover 6 m with 4 m + 2 m
- Cut length: 5 m + 0 mm trim = 5 m
- Grass bought: 4 × 5 + 2 × 5 = 30 m² (0 m² offcut)
- Seams: 2 strips − 1 = 1, 5 m long
How it works
- Strips run one way; the roll widths are combined to cover the other way at least once, choosing the set that buys the fewest m², then the fewest seams
- Each strip is cut to the run length plus the trimming allowance; grass bought = sum of widths × cut length
- Seams = strips − 1; seam length = seams × run length
- Tape rolls = seam length ÷ roll length; adhesive tubes = seam length ÷ metres per tube; both rounded up
- Infill (kg) = lawn area × kg per m²; sand layer (t) = area × depth × density
Roll widths and the pile direction drive the cost: try both directions to see the difference.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Roll widths you can buy | 2, 4 m | Common UK size Not yet checked against the source | From your product brief v2 L4 (2 m and 4 m roll widths). Check the product range. |
| Sharp sand density | 1.6 t/m3 Sources range 1.6–1.7 t/m3 | Typical value Not yet checked against the source | aggregatecalculator.co.uk aggregate density table (checked 19 October 2026) Damp sand bulks; order by weight. |