Get you a Jann's Netcraft catalog or LurePartsOnline. They both have blade size chart. On 1/8 which I use most of the time I use #1 and run some with #2 for real thump. On 1/16 I use #0 or #1. These are for Colorado or Indiana blades. On 1/16 I use up to #2 willow and on 1/8 I have started using #3and on some 3 1/2