(I'm assuming since you've mentioned the 50k that you'll be doing Construction, as I believe using it for smithing makes it last longer..?) Firstly, either calculate the difference between your current xp and your target xp, or set a level target (to have the game calculator do this for you). Once you have a digit, divide the number by 50,000 and you will be given a number of hammers necessary to reach that target, example: I need 847,291xp to get from Level 'X' to Level 'Y', I would do 847,921 / 50,000 = 16.95842 Clearly you would need 17 hammers to suffice for the .95842.. And a word of caution: Even if you may have 2 separate hammers in your inventory when you know one of them is not going to give the full bonus experience (EG, one item constructed requires 3% charge and you have only 2%), you will still lose the 1% and the other hammer will remain unused until you construct another item.. I hope some of this, if not all, has helped.. :)