I have been writing down when I change my blades and last night I changed it again. Looks like my blades last about a month. I sew every day and use the rotary cutter every day too. I also cut my left-over scraps when I've finished a quilt and anything smaller than 2" square gets sub-cut into smaller pieces for dog bed stuffing. So, I'm thinking I use the rotary cuttery alot. I also purchased an electric sharpener to see if that will help me save some $$$ on rotary cutters. I haven't used any of them that have been sharpened .....I figure I'll check them out towards the middle of the year to see if they give me a little more use. And, I agree with everyone.......replace that blade when it's dull......I'm worried that someday I'll push too hard and slice my finger!