There is no way to determine how much a piece of wool will shrink when felting it. There are too many variables like how hot the water is, how long it’s agitated, how the wool was processed before weaving, how refined is the wool, etc. This is one reason why Wild Thymes felts all the wool in every kit or bundle we sell. The other reason is we want our customers experience to be easy, happy, and successful. By felting all the wool ahead of time, we eliminate the customers’ need to stress over the felting process.
So, when buying yardage off the bolt for a project, always buy more than it calls for to allow for shrinkage during the felting process. We sell our wool either way – off the bolt (not felted) or felted.