What is the reduction ratio of the mulch produced by my Blower Joe SBJ603E? The reduction ratio of the mulch produced by your Blower Joe SBJ603E is 17:1. This means that the impeller in the blower can reduce the size of leaves by up to 17 times, effectively turning them into mulch. This is a very high reduction ratio, and it means that the SBJ603E is a very effective mulching blower. Related articles How many miles per hour (MPH) does the blower setting on my Blower Joe SBJ603E produce? What should I do if my Blower Joe SBJ603E gets clogged or jammed? What is the best way to clear a path with my Electric Snow Blower?