Turf is the one material with a deadline
Everything else on this site sits in a garage until you get round to it. Turf does not. It is a living thing, cut and rolled, and from the moment it is stacked on a pallet it is in the dark, compressed and heating up.
In summer you have about 24 hours. In cool damp weather maybe 48. Past that it yellows, and past a few days it is compost. Order it to arrive the morning you are laying it, and if the weather turns, unroll it grass-side up on a hard surface rather than leaving it stacked.
Which means the ground preparation has to be completely finished before the delivery arrives. Not mostly finished.
Wastage on turf is different from tiles
Five per cent is enough for a straight-sided rectangle. Ten if the lawn has curves, island beds, a path through it, or anything you have to cut around.
The difference from tiling is that turf offcuts genuinely cannot be reused. A triangular offcut can be pushed into a corner but it will not knit properly and it shows for a season. Better to plan for the cuts than to try to save them.
The part that costs more than the turf
Turf needs at least 100mm of decent topsoil under it for the roots to get into. On a 50 square metre lawn that is 5 cubic metres of soil, which is roughly seven and a half tonnes, and it will very likely cost more than the grass itself.
People consistently underestimate this. If the existing ground is builder's rubble, subsoil or compacted clay, the turf will look fine for six weeks and then go patchy and thin, because there is nothing for it to root into.
Which is a day of work before the pallet arrives
Clearing the old growth, breaking the ground up, getting that soil in and then firming and levelling it is most of the labour on the whole job, and it has to be finished when the delivery lands. That is the constraint this calculator exists to serve: order the quantity, then count backwards to the day you can take it.
The sequence itself, along with the laying pattern, the watering and the first cut, is on how to lay turf.
When to do it
Autumn is the best time in the UK: warm soil, reliable rain, and months to establish before it has to cope with anything. Spring is second. Midsummer works but demands watering every single day without exception. Winter is fine as long as the ground is not frozen or waterlogged, though it will sit and do nothing until things warm up.
Common questions
How many rolls of turf do I need?
Measure the lawn area and divide by the roll size, then add wastage for cuts. A UK turf roll is normally 1 square metre, so a 50 square metre lawn with 5 per cent wastage needs 53 rolls.
How much extra turf should I order?
Five per cent for a straight-sided lawn, ten if it has curves, beds or a path running through it. Turf is cut to shape at the edges and the offcuts cannot be reused, unlike a spare tile.
How long does turf last before it has to be laid?
Twenty four hours in summer, maybe forty eight in cool damp weather. It is a living thing rolled up in the dark and it starts to yellow and heat up almost immediately. Order it for the day you are laying it, not before.
How much topsoil do I need under turf?
At least 100mm of decent soil for the roots. On a 50 square metre lawn that is 5 cubic metres, which is a lot more than most people expect and usually the biggest cost of the job.
When is the best time to lay turf in the UK?
Autumn is best, then spring. Both give warm soil and reliable rain while it roots. Turf laid in midsummer needs watering every single day without fail, and turf laid on frozen ground will not root at all.