I still go to the Outervision Calculator "online". I think I actually had a subscription to it, but while I used to average building one system per year, I might now go two or three years between building projects.
Replacing HDDs with SSDs, the demise of SLI and Crossfire, and other factors promise less power draw so less required wattage of PSUs. You can do the arithmetic on a piece of paper, even so. If your CPU has a TDP rating of 95W, you might find it pulling 140W under strenuous overclock stress-tests once you come close to a practical limit. If you have more fans in the case as opposed to a few, be mindful of that component of power draw. My GTX 1070 over-clocked would never exceed 200W addition to total power-draw. Did I cover everything? I would think this summary includes most of it.
And just as a trivial footnote, some of the 650W units I have now were chosen with 2x SLI in mind, and I've since pulled out the spare graphics card.