Your proposed lawn area(s) should be measured as accurately as you can in square metres as the turfs themselves are approximately 1 square metre (equivalent to 1.196 sq yds).
For square or rectangular areas measure the length and the breadth of the area in metres and multiply the two together to give the number of square metres required.
It may be convenient if your lawn is not a total a square or rectangle to consider the lawn as a series of squares and/or rectangles then add them together to calculate the lawn area required and hence the number of turfs.
Don’t forget to add about 5% to the area to allow for cutting and wastage.
If you have an odd shaped lawn and cannot calculate the area perhaps Blackfords can help. Tel: 01793 772676.