"R" means resistance to heat flow. The higher the R-value, the greater the insulation power. Compare insulation R-values before you buy. There are other factors to consider. The amount of insulation you need depends mainly on your climate. Also, your fuel savings from insulation will depend on the climate, type and size of your home, your fuel use pattern, and family size. If you buy too much insulation, it will cost you more than what you'll save on fuel.

Compare more than just R-value in choosing your insulation. For example:

A recent study showed fiberglass batts loses up to 40% of its r-value simply being installed!

Cellulose insulation outperformed fiberglass in a side-by-side university study.