For planning purposes most would use 3-3.5%.But historically, we know that inflation goes through long cycles. There was a time back there in the 70s when inflation got much higher.Planning your portfolio to track changes in inflation rates has advantages. Otherwise if rates trend upward, you may need to do some belt tightening.Of course, the truth is no one knows the future 30 years out. Every plan will probably require some adjustment over the years. All we can hope for is to formulate a reasonable plan using the best tools available.