Turf Calculator

How Many Rolls of Turf Do I Need?

The usual answer is the lawn area plus 10%. B&Q's guide says the same: work out the area and add an extra 10% to allow for cutting and wastage. For a 5m × 4m lawn that is 22 rolls. It says nothing about how the rolls lay.

So this calculator lays the lawn out. Turf goes down in rows one roll wide, so each row is a run of whole rolls plus a cut piece, and the last row is cut narrower if the width is not a whole number of rolls. It tries several ways of staggering the joints and keeps the one that needs the fewest rolls. For the same lawn that comes to 22 rolls. Rows of whole rolls, such as a 6.56m × 4.88m lawn, need 32 and waste nothing.

No percentage is added on top, because the plan already packs the offcuts and adding 5% or 10% would count them twice. Turf is a fresh product, so an unused spare roll cannot be kept for a later job and is thrown away. The calculator shows a spare roll as its own line, like the architrave in the skirting calculator. Add it if you would rather have one in hand than be a piece short, or if the lawn has curved edges.

How the Layout Works

• Rows one roll wide. B&Q says to lay turf along all the edges first, with the longest sides parallel to the boundary. The calculator tries the rolls running each way for every section and uses the one that needs less turf.
• Joints staggered like brickwork. B&Q: "Stagger the joints in the same way as brickwork, from row to row." Each row starts with a different part-roll, and no joint sits within 300mm of a joint in the next row.
• No tiny pieces. B&Q advises against small pieces at edges, and to adjust lengths as you approach the boundary. No piece is shorter than 300mm. If a row would end in a sliver, the piece before it is shortened.
• Offcuts are reused. All pieces from all sections are packed into rolls together, longest first. A roll can be cut into two halves, each within a saw cut of half a roll.
• Several rectangles. An L-shaped or divided lawn is entered as up to four rectangles, laid separately, sharing offcuts.

What it does not do: it does not lay curved edges, and it does not allow for turf shrinking. Enter the bounding rectangles and raise the extra allowance for a curved lawn.

Preparing the Ground and the Topsoil

B&Q's guide says to dig over the area to a depth of about 15cm and remove all debris, large stones, weeds and old tree roots. The results give the volume of a 150mm bed under your lawn and a link that opens our topsoil calculator with the area and depth already entered. Fill any small gaps between rolls with topsoil and brush it level.

Turf Roll Sizes, With Sources

A roll is about 1 square metre, but the size varies by supplier. Every size in the dropdown has a supplier product page, and no product page means no dropdown entry. Check your supplier's roll size before ordering.

Common Lawn Sizes: Rolls Needed

Generated from the calculator above. Each lawn is one rectangle on 610 × 1640mm rolls, counted from the cutting plan with nothing added. The "area + 10%" column is the usual rule of thumb for comparison.

Use the calculator for your own lawn. Two rectangles, or a different roll size, change the answer more than you would expect. Going artificial instead? Our artificial grass calculator lays out the strips, seams and roll length.

Frequently Asked Questions

How many rolls of turf do I need?

The usual sum is the area plus 10%. B&Q's guide says to add an extra 10% for cutting and wastage. For a 5m × 4m lawn that is 22 rolls. It does not look at how the rolls actually lay. Turf is laid in rows one roll wide, the joints are staggered like brickwork, and every row ends with a cut piece. This calculator lays every row out and packs the pieces into rolls so short pieces come out of offcuts. The same lawn needs 22 rolls, and that already includes the cutting. Turf cannot be kept, so an unused spare roll is thrown away. The calculator shows one spare roll on its own line for you to add or not (23 for this lawn).

Which way should the rolls run?

B&Q's guide says to lay turf along all the edges first, with the longest sides of the turf parallel to the boundary line. Beyond that it is your choice, so the calculator tries both directions for each section and uses the one that needs less turf. You can also force one direction.

How do I stagger turf joints?

Stagger the joints in the same way as brickwork, from row to row, to avoid unsightly joins (B&Q). Start each row with a different part-roll. This calculator tries several patterns and keeps the one that needs the fewest rolls, with no joint closer than 300mm to a joint in the row beside it.

Why is there a shortest piece?

B&Q advises against small pieces at edges and says to adjust turf lengths as you approach the boundary to avoid finishing with a tiny section. The calculator never lays a piece shorter than 300mm. If a row would end in a sliver, the piece before it is shortened so both are usable.

How much topsoil do I need under turf?

B&Q says to dig over the area to a depth of about 15cm and remove debris, stones, weeds and old roots. The results include a link that opens our topsoil calculator with your lawn area and that 150mm depth already entered. For a 5m × 4m lawn that depth is 3.0 m³ before settling.

What size is a roll of turf?

About 1 square metre, but the size varies by supplier. Rolawn's Medallion turf roll is 610 × 1640mm, Tolleshunt Turf's classic lawn turf is 600 × 1670mm, and TFM sells a 1600 × 600mm roll. Each size has a product page listed below. Use Custom for anything else, and check your supplier before ordering.

Does it work for curved lawns?

Not exactly. Enter the lawn as one or more rectangles. Two or three rectangles cover an L-shaped or split lawn well, and turf offcuts are shared between them. For a curved edge, enter the bounding rectangle and raise the extra allowance, because the layout diagram is for the rectangles.