Artificial Grass Calculator

Artificial grass worked out in strips off a 2 or 4 m (or 15 ft) roll: length to buy, square metres or feet, seams, joining tape and infill.

Artificial grass comes in rolls of fixed width, usually 2 m or 4 m in the UK and Australia and around 15 ft in the US, and every strip must lie with the pile facing the same way. So, like carpet, what you buy depends on how your lawn fits the roll. A 6 × 5 m lawn from a 4 m roll needs two strips 5.1 m long, 10.2 m off the roll and 40.8 m² of grass for a 30 m² lawn. Enter your areas and roll width and the calculator lays out each area both ways, picks the one that uses less, and gives the length to buy, the area, the seams, joining tape and the infill sand.

Units
Bag sizes
Area
m
m
mm
Off the roll
10.2 m

4 m wide

To buy
40.8 m²

36% more than the lawn

Infill
150 kg

joining tape 5 m

Seams
1

30 m² of lawn

How it was worked out
  1. Room: 6 × 5 m; strips run along the width: 2 strips of 5.1 m = 10.2 m off the roll, 1 seam
  2. 10.2 m × 4 m roll = 40.8 m²
  3. Infill: 30 m² × 5 kg per m² = 150 kg

Every strip must lie with the pile facing the same way, so offcuts are only used where that still holds. Infill rates vary by product: follow the maker's figure. Work out the sub-base with the crusher dust, Type 1 or road base calculators.

Common use cases

  • Order artificial grass for a garden, balcony or play area
  • Compare 2 m and 4 m wide rolls for your lawn
  • Work out joining tape and infill at the same time
  • Check an installer's quote

How to use

  1. Choose your units and country (for the usual roll widths).
  2. Enter each area's length and width.
  3. Pick the roll width and trim allowance, and the infill rate from your product.
  4. Read the length off the roll, the area to buy, joining tape and infill.

FAQ

How do I work out how much artificial grass I need?

Work out how many roll widths cover the lawn's width, then multiply by the length plus a little for trimming. Try both directions and choose the one that uses less grass, keeping all strips with the pile facing the same way, ideally towards the house.

What goes under artificial grass?

UK and Australian guides commonly use about 75 to 100 mm of compacted crushed stone or sub-base, topped with 20 to 25 mm of sharp sand or crusher dust, and a weed membrane. Follow your grass supplier's instructions. The Type 1, road base and crusher dust calculators work out these layers.

How much infill sand does artificial grass need?

It depends on the pile height and product, often a few kilograms per square metre. Use the rate your manufacturer gives; the calculator starts at 5 kg per m².

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