Turf calculator rolls for any lawn

How the turf calculator counts the rolls

It adds up the area of every shape you enter, adds your wastage allowance once for the whole lawn, divides by the area of one roll, and rounds up to a whole roll. With the topsoil bed set to Yes, the default, it also gives the volume and weight of a 100mm soil bed under the lawn's measured area.

The default roll is 1m², the size in the TGA's specification and Rolawn's standard roll. The default wastage is 5%, the same figure Rolawn's own product calculator adds for cutting and shaping. Here is a plain rectangular back lawn of 9m by 5m.

• Area: 9 × 5 = 45m².
• Plus 5% wastage: 45 × 1.05 = 47.25m².
• Rolls: 47.25 ÷ 1m² = 47.25, so 48 rolls.
• Topsoil for a 100mm bed: 45 × 0.100 = 4.50m³, which at 1.5 tonnes per m³ is 6.75 tonnes. The topsoil calculator turns that into bulk bags with a settlement margin.

Check the roll size before you order

Most UK garden turf comes in rolls of about one square metre, but not all of it. The Turfgrass Growers Association's specification for cultivated turf describes a small roll as 600mm wide and 1.65m long, a total of 1m². Rolawn cuts its Medallion turf at 610mm by 1640mm, also about 1m², around 12.5mm thick, and each roll weighs 15 to 20kg depending on moisture.

Some rolls are smaller. Turfonline points out that B&Q's turf measures 610mm by 1370mm, about 0.8m². On the same 9m by 5m lawn, that is 47.25 ÷ 0.836 = 56.5, so 57 rolls, nine more than the 1m² answer. Big rolls for large areas are cut to sizes agreed with the grower.

Order by square metres, not by a count of rolls you have not measured. The calculator offers four sizes: 1m², 600 × 1650mm, 610 × 1640mm and 610 × 1370mm. If your roll is none of these, take the m² with wastage from the working and divide it by the area of one of your rolls.

Measuring circles, curves and awkward lawns

Split the lawn into simple shapes, measure each one, and add them. For a circle, measure straight across the middle and halve it to get the radius. The area is π, about 3.1416, times the radius times the radius. A round lawn 4m across is 3.1416 × 2 × 2 = 12.57m².

Curves and corners create more offcuts than straight edges. Use 5% for a rectangle and 10% where the edges curve. For a curved lawn of the 4m circle alone: 12.57 × 1.10 = 13.82, so 14 rolls.

Add that circle to the 9m by 5m rectangle and the lawn is 57.57m². With 5% on the whole thing it comes to 60.44m², or 61 rolls. The TGA's specification fills small gaps with topsoil rather than slivers of turf, so the allowance is for cutting around edges, not for plugging holes.

When to lay turf, and how fast

The best time is mid-autumn. The RHS's guide to lawns from turf says turf can go down any time from mid-autumn to early spring, as long as the soil is not too wet or frosty, and advises against laying from mid-spring to early autumn, when it needs repeated watering to establish.

Growers sell it all year. Rolawn's guidance on when to lay turf is that it can be laid in any month but never onto frozen ground, and that hot, dry spells need extra care. For a summer job, price in the watering.

Turf does not keep. The TGA specification says it should reach site within 36 hours of being lifted, and be laid on the day of delivery in hot weather. Rolawn says roll it out immediately in spring and summer, and within 24 hours in autumn and winter. Have the ground finished before you book the delivery.

Preparing the ground and laying it

The rolls are the easy part to get right. The lawn lives or dies on the soil under it.

• Topsoil depth: the TGA wants a minimum of 100mm of topsoil, and any surface stones bigger than 35mm taken out. That is the 100mm bed the calculator offers.
• Cultivate first: the RHS says to dig or rotovate to 20 to 25cm so nothing is compacted, then let the ground settle, ideally for five to six weeks.
• Feed: the TGA spreads a pre-turfing fertiliser over the area before the turf goes down.
• Lay like brickwork: both the TGA and the RHS say to stagger the joints from row to row and push the edges tight, and to work off planks laid on the new turf so you do not leave footprints.
• Water straight away: the TGA asks for the soil to be damp to 100mm after the first watering, then morning and early evening watering, less often as the first 28 days go on, and never so much that it waterlogs.
• Leave it alone: the RHS notes that little mowing is needed in spring and autumn, so turf laid then can be left undisturbed for several weeks while it roots.

What the turf calculator will not tell you

It counts rolls. It does not plan where the cuts fall, price the turf or the delivery, or allow for an area you have not measured. It is for natural turf. Artificial grass is sold by width off a long roll, so use the supplier's own measuring guide for that.

If you lay lawns for a living, put the turf, the soil and your time on the quote template. To set the rate you charge for a two-day lawn job, start with the day rate calculator.

• Measure twice. A metre out on the length of a 5m wide lawn is five rolls.
• Weigh up the pallet. At 15 to 20kg a roll, 48 rolls is the best part of a tonne to carry through to the back garden.

Common questions