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Step 1: measure your lawn
Measure the longest length and the widest width of the area in metres (or feet — the calculator converts either way). If your garden is L-shaped or an odd shape, split it into rectangles. Work out each rectangle on its own, then add them together. Always round your measurements up, never down. If you round down, you risk ending up short.
Step 2: understand why length × width isn't enough
Artificial grass is made on rolls of a set width — in the UK almost always 1m, 2m or 4m wide (some suppliers also do 1.5m and 3m). The shop cuts the roll to whatever length you ask for, but the width is fixed. That matters because you pay for the full width of the roll even if your lawn is narrower.
So if your lawn is 4.2m wide, one 4m roll will not cover it. You would need a second strip of grass to cover the rest — and now you are buying much more than your tape measure suggested. This is why a simple length × width sum almost always leaves you short.
Step 3: think in "strips" and joins
You cover a lawn in strips, a bit like laying carpet. Each strip is one roll wide and runs the length of your lawn. Every strip must run the same way, so the pile (the grass blades themselves) all leans in the same direction. If it doesn't, the light catches each piece differently and the lawn looks patchy. Where two strips meet you get a join (also called a seam — the line where two pieces are taped and glued together). The number of strips decides how many joins you'll have:
- A wider roll (4m) usually means fewer joins — a neater finish, but you may pay for more grass than you use if your lawn is narrow.
- A narrower roll (1m or 2m) often wastes less on small or narrow areas, but you'll have more joins to tape and glue.
A worked example
Say your lawn is 6m long and 5m wide:
- 1m wide: 5 strips of 1m × 6m = 30 m² (a perfect fit, but 4 joins).
- 3m wide: 2 strips of 3m × 6m = 36 m² (6 m² spare, just 1 join).
- 4m wide: 2 strips of 4m × 6m = 48 m² (18 m² spare, 1 join).
Same lawn, very different amounts. That is why it pays to compare roll widths rather than guess.
Don't forget a little extra
Shops usually sell lengths by the whole metre, so you get a small amount spare without asking for it. Even so, measure carefully and allow a little extra. You'll need it for cutting clean edges and for making sure the pile on every piece leans the same way.
Get your exact amount in seconds →The calculator compares 1m, 2m, 3m and 4m rolls for your garden and ranks them by cost and joins. grass calculatorGet my answer — free →
How do I measure an odd-shaped garden?
Break it into rectangles, work out each one, then add the results together. Round up at every step.
Should I add extra for waste?
Buying by whole-metre lengths usually gives you a little spare. Allow a touch more for trimming, and for keeping the pile leaning the same way, if your garden is a fiddly shape.
Is wider always better?
No. Wider rolls mean fewer joins, but they can waste grass on narrow lawns. The best width depends on your exact measurements — compare them in the calculator.
Rather not do it yourself?
Measuring up is the easy bit. The hard graft is digging out the old lawn and packing down a firm base of stone for the grass to sit on. Post the job free and local landscapers reply with quotes, so you can compare real prices against our estimate.
Find a tradesperson for this project →