Trying to determine how far a Pokemon is from you in Pokemon GO isn’t as straightforward as you might expect. It’s also worth mentioning that the game doesn’t have a directional GPS that lets you know which direction you should be moving towards in order to track a particular Pokemon, but there are a couple of indicators that will make your life a bit easier.
When you’re out and about, tap the grey box in the corner of your screen to see if there are any Pokemon in the vicinity. This will bring up a list of Pokemon that are near you. You’ll also see some footsteps below the icon of each Pokemon, indicating how far they are from you. Zero footsteps means you should be able to interact with the Pokemon from where you are, and one and two steps mean you’re getting closer to them. If there are three footsteps, that means a Pokemon is in your vicinity, but is currently out of your immediate reach. You’ll have to start walking to find them.
Another good thing to note is that the top left Pokemon on the list is the one you’re closest too, and the bottom right is the one furthest from you. Since there’s no directional GPS, you’ll have to start walking to see if you can reduce the number of footsteps beneath the icon of the Pokemon you want. If you’re moving in the right direction, the target Pokemon will move up the list, closer to the top left corner. Continue moving in that direction to reduce the number of footsteps and determine where exactly it is. This is currently the best way to track down Pokemon, and with a little trial and error, you should be able to find what you’re looking for.
Once you’re near the Pokemon, use your radar in Pokemon GO to seek it out and catch it.