Infusion gives you 80% of the infused weapons light rounded up. Meaning 305 infused into a 298 would be 305-298 = 7 •.8 = 5.6 (rounded) 298 + 6 =304 I'm sure it's rounded up because it couldn't be rounded down due to 1 light higher gear wouldn't gain any higher light. Bump if you found this helpful. Edit : If you aren't a mathlete, this calculator can help - http://www.destinyinfused.com/. It is better to wait on infusing until you have something that is substantially higher in power in order to get more out of each infusion. (Taken from someone on the help forum)