Advanced options
Artificial grass comes on 4m and 2m wide rolls, bought as full-width cuts like carpet. All pieces must run the same pile direction; joins use joining tape and adhesive. The base is the real job: excavate 50-75mm, type 1 sub-base, then a sharp sand or granite dust laying course.
What The Artificial Grass Calculator Works Out
- Lawn area: length x width in square metres, the figure the base materials and installation are priced on.
- Grass to order: full-width cuts from a 4m roll by the longer dimension plus 10cm trim, like carpet, rather than the lawn's neat area. A 5 x 4m lawn takes one 4m-wide cut just over 5m long, about 20.4 m2; wider lawns take several strips joined with tape and adhesive, all running the same pile direction with the pile leaning towards the main viewpoint.
- Base materials and cost: about 60mm of compacted MOT Type 1 (around 2 tonnes per m3) and a 40mm laying course of sharp sand in 25kg bags, plus the grass at your price per m2. The base is most of the labour and most of the longevity, and doubles as the drainage design.
- Trade-offs: good grass on a proper base lasts 10 to 15 years, gets genuinely hot in direct summer sun, needs occasional brushing, and gives nothing back to pollinators or soil life, a point the RHS presses. Pet owners want a denser pile and enzyme cleaners.
- Roll width (advanced): switch to 2m rolls, or let the calculator pick whichever of 2m and 4m wastes least for your lawn shape. A 2.2m-wide lawn is far cheaper from a 2m roll plus a strip than from a 4m roll.
- Trim allowance (advanced): change the 10cm extra on the length; allow more for lawns with curved or irregular ends.
- Offcut waste (advanced): the difference between what you buy and the lawn area, as square metres and a percentage, to compare roll-width options.
- Joins and tape (advanced): one join per extra strip, with the metres of joining tape and 5kg tubs of adhesive (about 10 metres of join per tub) needed.
- Base in bulk bags (advanced): edit the sub-base and laying course depths (50 to 75mm of Type 1 and 20 to 40mm of sand or granite dust are typical) to get tonnes and 850kg bulk bags of each, plus the total excavation depth including the grass itself.
- Sand infill and installation (advanced): kiln-dried sand at your rate per m2 (most products take 4 to 8 kg/m2 to hold the pile up and keep it cool) in 25kg bags, and the lawn area x an installer's rate. Fully installed artificial lawns in the UK commonly cost GBP 40 to GBP 70 per m2 including the base.
Further reading: RHS on artificial grass.