2.5" to 3.5" for me. It varies a lot with the type of knife. A traditional slipjoint is in the 2-2.5" for me, a one hand folder, I prefer 2.8-3.2", but can go up to 3.5" if I am expecting a little bit more work that day. My most common EDC knives are: BM 558 Mini-Ritter, 2.9" blade, BM 13960 Osborne, 3.1" blade. Case Peanut, 2.2" blade, Case Sway Back Jack, 2.5" blade, Spyderco UKPK 3" blade.