You stroll along the mall and open up your Pokemon Go app when a wild Pidgeotto appears! You check its CP, it says '520'. After a bunch of tries, sad news for your lost Pokeballs, you finally got it and checked out your Pokemon bag. You find that you have a 320CP Pidgey next to the new 520CP Pidgeotto. You now ask, 'Should I power up my Pidgeotto or should I keep collecting Pidgey candies so I can evolve and possibly surpass my current Pidgeotto?'
How do you increase CP by the way?
There are two ways to groom or power up your Pokemon in Pokemon Go. One is to just power up. This requires Stardust and Candy, usually 2 candies, to increase your CP, or Combat Points for those who are still learning. The other way is to evolve. This evolves your Pokemon into the next level, provided there is room for evolution, and at the same time increase your Pokemon's CP. How the CP increases from one Pokemon to another so it is uncertain if an evolution or a power up is optimal for a certain Pokemon in Pokemon Go.
If only you have a tool to help you.
Fortunately, the good guys at PokeAssistant.com have come up with an online application that would estimate the probability of CP increase when you decide to evolve your Pokemon. You can click here for the CP calculator. To quote the usage: "The tool shows what CP a Pokemon is likely to evolve into (and has evolved from) based on samples in PA's database. Not all Pokemon scale up in CP the same during evolution. Some species increase CP by 50%, others by 300%. This tool puts it in one place to help you decide."
This tool is being updated on a regular basis so it is possible that one of your Pokemon is not yet in the database.