As above, Hawke Chairgun will show you what's happening on a graph & explain better than pages written here, just play with it changing the zero range, muzzle energy &/or pellet weight to see the changes.
very roughly speaking .177 zero at around 32yds, .22 zero around 26yds for the flattest, longest point blank range (PBR) which is where the pellet is within 1/2 inch of the point of aim.

When you get a new gun you usually need to start a zero at about 10yds to even have the pellet hit a sheet of A4 paper, because at 25-30yds with a new scope the aim could be several feet off.