Quick answer: Measure the longest length and widest width in metres, add about 10 to 15 cm to each for trimming, then work out how 2 m or 4 m wide rolls will cover that rectangle with every piece’s pile facing the same way. You order roll width × cut length for each piece, not just the lawn’s square metres.
Artificial grass is sold off the roll in fixed widths, so a lawn of 42 m² rarely means an order of exactly 42 m². The skill is in planning the cuts. This guide walks through measuring, choosing a layout and estimating the extras, and it belongs to our wider set of garden and outdoor measuring guides.
What do you need to measure for artificial grass?
- A long tape measure, ideally 10 m or more, so you can take each dimension in one pull
- A helper to hold the end of the tape straight and level
- Pegs and string to mark straight edges where there is no wall or path
- Squared paper or a notes app to sketch the shape and record every figure
- A compass app or a note of which way the house faces, to decide the pile direction
A steel tape is fine for small areas, but a fibreglass surveyor’s tape is easier on long runs. If the markings confuse you, our guide to reading a tape measure explains metric and imperial scales.
How do you measure a garden for artificial grass?
Measure the full length and width at their longest and widest points, record them in metres, then add a trimming allowance. Follow these steps in order.
- Sketch the area. Draw the outline roughly, marking the house, paths, beds and any obstacles such as a shed or tree.
- Decide where the grass will stop. Mark the finished edge against patios, borders and edging, not the current edge of a scruffy lawn.
- Measure the length. Run the tape from the house side to the far end. Take it at both sides and in the middle, and use the largest figure.
- Measure the width. Do the same across the garden at the near end, the middle and the far end. Again, keep the largest figure.
- Add the allowance. Add about 10 to 15 cm to each measurement so the edges can be trimmed neatly. A 5.8 m width becomes 5.9 m or a little more.
- Note the viewing direction. Mark where you will see the lawn from most often, usually the back door or living room window.
- Plan the pieces. Using the roll widths below, sketch how the pieces will run and where the seams will fall.
How wide are artificial grass rolls in the UK?
Most artificial grass in the UK is sold in rolls 2 m or 4 m wide, cut to whatever length you order. Some ranges also come in a 5 m width, so check the product page before you plan. Because the width is fixed, your planning question is always: how many roll widths do I need to cover one direction, and how long must each piece be to cover the other?
| Roll width | In feet and inches | Area per metre of length | Good for |
|---|---|---|---|
| 2 m | 6 ft 6¾ in | 2 m² | Narrow strips, topping up a 4 m width, small balconies |
| 4 m | 13 ft 1½ in | 4 m² | Most back gardens, with fewer seams |
| 5 m (some ranges) | 16 ft 4¾ in | 5 m² | Wider lawns where a single piece avoids a join |
Imperial figures are rounded to the nearest quarter inch; the cm to feet converter gives exact values if a supplier quotes in feet.
How do you work out how much artificial grass to order?
Choose which direction the rolls will run, then add up roll width × cut length for each piece. Take the lawn in the diagram above: 5.8 m wide and 7.4 m deep, so 5.9 m × 7.5 m with the allowance. Its true area is 42.92 m², but two sensible layouts give different orders.
| Layout | Pieces | Ordered area | Offcut beyond the lawn | Pile direction |
|---|---|---|---|---|
| A: rolls run away from the house | 4 m × 7.5 m + 2 m × 7.5 m | 45.0 m² | 2.08 m² | Towards the house |
| B: rolls run across the garden | 4 m × 5.9 m + 4 m × 5.9 m | 47.2 m² | 4.28 m² | Sideways across the view |
Layout A wins on both counts here: less waste and the pile faces the house. Note how tight the margin is, though. If the garden were 6.1 m wide instead of 5.8 m, a 4 m plus 2 m layout would be 6 m wide and fall short, forcing two 4 m widths. That is why the trimming allowance matters before you plan, not after.
Both layouts have one seam, which is 7.5 m long in layout A and 5.9 m in layout B. You will need joining tape at least as long as each seam and enough adhesive to cover it, so check the coverage stated on the adhesive; small tubes may cover only a few metres of join.
Which way should the pile face?
Point the pile towards the place you view the lawn from most, which for a back garden is usually the house. Artificial grass blades lean slightly in one direction along the length of the roll. Looking into the pile shows the fullest, greenest face; looking with it can make the lawn look shinier and thinner.
Every piece must lean the same way. If two pieces meet with their pile in opposite directions, the seam shows as a line where the colour changes. Suppliers also advise ordering all pieces from the same roll or batch so the shade matches, which is another reason to order everything at once rather than topping up later.
How do you measure an L-shaped or curved lawn?
Split the shape into rectangles that each suit a roll width, keep the pile running the same way in every piece, and measure curves to their widest point. Curves are always cut on site, so treat a curved edge as if it were straight at its outermost point.
In this example the left piece runs the full 6 m depth plus 10 cm. The right-hand area is only 3.5 m deep beside the patio, so the second piece is 3.6 m long. It still has to come off a 4 m roll, which leaves a 0.9 m wide offcut beyond the lawn edge, but that is less wasteful than covering the whole 7 m × 6 m rectangle and cutting out the patio.
What else do you need to measure for?
Beyond the grass itself, measure for the base materials, the edging and the joins. These are often forgotten until the day of the install.
- Base materials. A typical lawn installation on soil uses a compacted aggregate sub-base with a laying course of sharp sand or granite dust on top; one UK retailer recommends 3.5 to 5 cm of sharp sand. Volume is area × depth, so a 42.92 m² lawn with a 3 cm laying course needs about 1.29 m³. Our gravel per square metre guide shows how to turn volume into tonnes.
- Edging. Measure the perimeter that is not already held by a wall, path or patio. The full perimeter of the 5.8 m × 7.4 m lawn is 26.4 m, but if the house side meets a patio you only need edging on the other three sides.
- Weed membrane. Order roughly the same area as the lawn, plus overlaps where strips meet.
- Joining tape and adhesive. Add up the length of every seam and allow a little extra.
If you are lifting an existing lawn and the ground needs building up first, the topsoil volume guide uses the same length × width × depth method.
Common mistakes to avoid
- Ordering the lawn’s area instead of the cuts. A 42.92 m² lawn still needed 45 m² in the example above.
- Measuring once. Gardens are rarely square. Measure each dimension in at least three places and use the largest.
- Forgetting the trimming allowance. Without 10 to 15 cm spare, a slightly out-of-square fence can leave a gap along one edge.
- Mixing pile directions. Turning one piece round to save a few square metres leaves a visible stripe at the seam.
- Putting a seam in the busiest spot. Plan joins away from the main walking route and the view from the house where you can.
Frequently asked questions
How much extra artificial grass should I order?
Add about 10 to 15 cm to each measurement for trimming, then plan the cuts using the roll width. The extra beyond the lawn’s own area depends on how well the roll widths fit your garden.
What widths does artificial grass come in?
Most UK artificial grass comes in 2 m and 4 m widths, cut to the length you order. Some ranges are also available 5 m wide.
Which way should artificial grass pile face?
Face the pile towards where you usually view the lawn, normally the house for a back garden. All pieces must have the pile running the same way so the joins do not show.
How do I measure a curved lawn for artificial grass?
Measure to the widest and longest points of the curve as if the edge were straight, then plan rectangular pieces to cover it. The curve is cut on site once the grass is laid out.
Can I join two pieces of artificial grass?
Yes. Pieces are butted together, not overlapped, and fixed with joining tape and adhesive underneath. Keep the pile running the same way on both pieces.
Sources
- Artificial grass: measuring and fitting, Online Carpets (roll widths, trimming allowance, joining)
- Artificial grass pile direction, Grass Direct
- National Physical Laboratory, for the metre and exact imperial conversions
More Garden and Outdoor guides
- How to Measure for a Fence Panel (UK): Panels and Posts
- How to Measure for Artificial Grass: UK Roll Guide
- How Much Gravel Per Square Metre? UK Calculator
- How Much Topsoil Do I Need? UK Calculator and Guide
- How to Measure Lawn Size for Turf (UK Calculator)
- How to Measure a Garden in Square Metres (UK Guide)