How to measure for artificial grass
Measure the area to be covered out to its fixed edges: the timber, steel or brick edging the grass will be pinned or glued to. For a rectangle, take the length (A) and the width (B). Measure the width at both ends and use the bigger figure, because the grass is cut from a straight-sided roll and a strip that is too short can’t be stretched.
An L-shaped lawn is the full rectangle minus the missing corner. A round lawn is a circle: measure straight across the middle. An oval lawn is an oval: the longest length and the widest width. For any other outline, measure the smallest rectangle that contains it. You will be cutting the shape out of rectangular strips anyway, so that rectangle is close to what you actually buy.
If you measure in feet and inches, switch the units at the top; the answer still comes out in metres of roll.
Artificial grass fixings and infill
Alongside the grass itself, every lawn needs fixing pins round the edges, tape and adhesive under every join, and usually a sand infill brushed into the pile. These are typical figures from UK suppliers’ fitting guides, plus our own suggested trimming allowances, and the calculator starts from them.
| Use | Typical figure | Used for | Apply |
|---|---|---|---|
| Roll widths | 2 m, 4 m or 5 m | Strips cut to length and laid side by side | |
| Extra length on each stripOur suggestion | 100–150 mm | Trimming the ends to fit the edging | |
| Width trimmed at each joinOur suggestion | 50 mm | Cutting the factory edge back before joining | |
| Fixing pins | One every 300–500 mm | Along the edges and every join | |
| Joining tape | Sold by the metre | Under the full length of every join | |
| Joining adhesive | One tube per 1.5–2 m of join | Glues the grass to the tape | |
| Kiln-dried sand infill | 5–8 kg/m² | Brushed down into the pile |
If the instructions for your grass give other figures, type them in: the maker knows its own product best.
Choosing a roll width
Artificial grass comes in rolls of fixed widths, cut to whatever length you order. A wider roll means fewer joins, and joins are the hardest part to hide. Wide rolls are heavy, though, so check you can get one through the house or down the side passage.
With The way that needs least grass chosen, the calculator tries the strips both ways, along the length and across the width, and keeps whichever needs the shorter total. If you want the strips to run a particular way, for example so the pile leans towards the house, choose Along the length (A) or Along the width (B) and see how much extra grass that takes.
Why the pile must all lean one way
The fibres lean slightly one way, so the colour looks different from each side. Lay every strip with the pile leaning the same way, or each join shows as a stripe. That is why the calculator doesn’t turn offcuts round to fill gaps: it would save grass but spoil the lawn.
Joins, tape and adhesive
Where two strips meet, they are joined over a strip of joining tape laid underneath, with adhesive spread on the tape. The calculator measures each join along the shorter of the two strips, lists that length of tape (UK suppliers sell it by the metre), and adds adhesive at the rate in Tippers’ fitting guide, one tube per 1.5–2 m of join. It uses the shorter length, so you won’t run short.
Each join also costs a little width, because the factory edges are cut back before the strips are butted together: the calculator allows 50 mm at each join. It also adds extra length to every strip so the ends can be trimmed to fit; we suggest 100–150 mm, and the calculator starts at the shorter figure. No UK guide we found gives figures for these, so they are our suggestion: change Width trimmed at each join and Extra length on each strip in step 2 if your fitter works differently.
Joins need pinning too, so the pins are counted along each join as well as round the edges. If your lawn fits in a single strip, there is no tape or adhesive on the list at all, which is one more reason to look at the wider rolls.
Artificial grass infill
Most artificial grass is finished with kiln-dried sand brushed down into the pile. It weighs the grass down, holds the backing in place and helps the fibres stand up. UK fitting guides give 5–8 kg/m²: Namgrass suggests the bottom of that range and Tippers a little more. The calculator starts at the lower end of the Tippers range and works out the 25 kg bags.
Some grasses are made to be laid without infill, and some makers ask for a particular sand, so check the instructions and switch the infill off if it isn’t needed. Use kiln-dried sand rather than building or sharp sand: it is dry, so it runs down between the fibres instead of clogging on top.
What this artificial grass calculator does not cover
This artificial grass calculator covers the grass and what holds it down, not the ground underneath. Fitting guides lay artificial grass on a compacted sub-base of MOT type 1 with a thinner layer of fine crushed stone on top, and the depths depend on your ground and on the grass maker’s guide.
Work out the type 1 with the type 1 calculator. Treat any depths you are given as a guide: drainage, soft ground and slopes all change what is needed, so check your plan with the supplier or an installer.
Worked example: a rectangular lawn in two strips
Here is the full calculation for a rectangular back lawn using a 4 m wide roll, with the strips laid the way that needs least grass, sand infill and nothing extra on top. Every line comes from the same code that runs the calculator above, so the figures always match.
- Area 7 m × 5 m = 35.00 m²
- Strips 4 m wide roll, pile all one way, 50 mm trimmed at each join, 100 mm added to each strip for trimming the ends = 2 strips, 10.20 m
- Plus any extra 10.20 m + 0% = 10.2 m
- Joins where strips meet, along the shorter strip = 5.0 m of joins
- Tape and adhesive 5.0 m + 0%; one tube for every 1.5 m = 5 metres of joining tape, 4 tubes of adhesive
- Pins (24.0 m of edges + 5.0 m of joins) ÷ 300 mm = 97 pins
- Infill 35.00 m² × 6 kg/m² = 210 kg → 9 bags
On the list:
- 11metres of 4 m wide roll of artificial grass2 strips, 10.2 m cut length
- 5metres of joining tape (sold by the metre)5.0 m of joins
- 4tubes of adhesiveabout 1.5 m of join each
- 97fixing pinsevery 300 mm along 29.0 m of edges and joins
- 925 kg bags of kiln-dried sand210 kg at 6 kg/m²
Notice that the calculator runs the strips across the lawn rather than along it, because two short strips need less grass than two long ones. The second strip is wider than the gap it fills, so you trim the spare off one edge: that offcut is the trade-off for having a single join. Notice too that each strip is cut a little longer than the lawn, so the ends can be trimmed to fit against the edging.
UK artificial grass roll sizes
In the UK, artificial grass is sold from rolls of a few standard widths and cut to the length you order. Joining tape is sold by the metre, adhesive by the tube, and kiln-dried sand in small bags you can carry.
| Product | Size | Good for |
|---|---|---|
| 2 m wide roll | 2 m wide | Cut to the length you order. |
| 4 m wide roll | 4 m wide | Cut to the length you order. |
| 5 m wide roll | 5 m wide | Cut to the length you order. |
| Joining tape | sold by the metre | Goes under the joins between strips. |
| Joining adhesive | one tube for about 1.5–2 m of join | Glues the grass to the tape. |
| Small bag, 25 kg | 25 kg | Merchant “handy bag” or trade pack. |
Not every grass is made in every width, so check the widths of the grass you like before you plan the strips. If it only comes in one, choose that width in step 2 and let the calculator lay out the strips.
Common mistakes when ordering artificial grass
- Ordering by square metres. Grass comes off a roll of fixed width, so what you buy is strip lengths. A lawn slightly wider than one roll needs a second strip.
- Measuring short. A strip cut too short can’t be stretched. Measure to the edging at the widest point, and add some extra for curves.
- Cutting strips to the exact length. Leave the ends long and trim them in place against the edging. The calculator already adds a little to every strip for this.
- Skipping the base. Grass laid straight onto soil goes lumpy and lets weeds through. Plan the sub-base before you order the grass.
- Using the wrong sand. Damp building sand clumps on top of the pile instead of falling between the fibres. Use kiln-dried sand.
What else you'll need
- A compacted sub-base. MOT type 1 goes under the grass; the type 1 calculator works out the tonnes.
- More kiln-dried sand if you are also filling paving joints: use the sand calculator.
- Weed membrane between the base and the grass, if your grass maker recommends one.
- Edging in treated timber, steel or plastic to fix the edges of the grass to.
- A sharp knife with spare blades, and a stiff brush for working in the infill.
Last checked 28 October 2026