Here's the DMG to hit table for fighter types: The 5% check mark seems to be wonky. To hit AC 0 for 1st level fighter, it should be 20 . Whether you are using the attack matrix or THAC0. I have tried this and gotten the same for both. If you are using the 5% improvement per level as we have done since my now tired and brutally battered DMG arrived in my hands in December 1979. To hit AC 0 is: 19 for level 2 18 for level 3 Now here are a 2nd level fighter and a 1st level Paladin, both fighters: Here are their THAC0. 19 for a 1st level fighter - huh? - and 19 for a 2nd level fighter. It should be 20 and 19, respectively. As you continue to advance with 5% turned on, you don't advance on an even number, but advance by 2 on an odd number. The DMG clearly states you advance per level. I don't know about other classes, but I think this needs to be corrected. With 5% turned off, the levels advance by 10% every second level.