I have seen video that says we can use an IV calculator such as:
to first find out the possible perfection %, and then keep on "power up" or "evolve", and use the Refine button and you can narrow down the real number for this Pokemon.
For example, it could be 67.8%, 82.2%, 94.8% (just an example), and after some power up and/or evolve, you can narrow down it to 82.2%
But I also have seen a video that says you can go to some website and type in your gmail log in, and it will tell you the perfection % of every single Pokemon that you have. So I presume that will mean you don't have to waste stardust and candies to do the narrow down.
Is it really possible to know the perfection % without using stardust and candies to do the narrow down?