A shop will measure it and hone it for you, but they will want to sell you a piston kit with mark-up.
I recommend picking up the tools for measuring the cylinder, and learning how to use them properly. Even if it is just a rough measurement.
I use telescoping 't-gauges' and a vernier caliper set for a quick shot at the number.
If you want to get a more accurate number, buy a set of micrometers instead of calipers.
Absolutely nothing you or any of us can do without the cylinder spec.
-BIG DAN