To calculate the number of packages of insulation needed, determine the area if the attic (m²) to be insulated, by multiplying the length by its width.

The number of m² of insulation material is clearly marked on each package. Divide the total attic area to be insulated by the m² in a package to determine the number of packages required (don't forget to round up to the nearest whole package). Subtract approximately 10% to allow for roof trusses.


Calculating Property Area

Simply pace out the front (or rear) and one side of your house. Multiply the figures together to give the area in square metres. e.g. 10 paces by 5 paces = 50m²


Below is a table showing approximately how many bags of ceiling insulation you will need to insulate a given ceiling space.

Ceiling Insulation Calculator Table

ProductPacks Required / #m²
 R-Value    Width   50m²75m²100m²125m²150m²175m²200m²
R-2.5430mm4579101214
R-2.5580mm34578910
R-3.0430mm57911121618
R-3.0580mm4578101213
R-3.5430mm581012151719
R-3.5580mm4689111314
R-4.0430mm691214172023
R-4.0580mm57911131517
R-5.0430mm10141923283237
R-5.0580mm7111417212427
R-6.0430mm9131721253034
R-6.0580mm7101316192225