If you are referring to the standard indoor targets we shoot here, like the one below, then they are shot at 25yds.
They are a 10 shot card with the center diagram allowed for 3 non-scoring sighters.
The card measures 310mm x 210mm.
Each diagram measures Ø47mm
This what you were wanting to know?

Scoring is determined by the outer edge of the bullet hole.
If the outer edge cuts the ring then it is out and scores the lower value.
The two innermost rings which are closer together determine whether the shot scores a 10 or a 10.1 (inner bull) thus the perfect card will yield a possible 100.10
Note the following pictures and their relevant scores.