How it works out those numbers

The breaker comes from the continuous-load rule: car charging runs for more than three hours, so the circuit is sized at 125% of the draw and rounded up to a standard rating. That is the whole ofbreaker sizing.

The minimum conductor is the smallest gauge whose ampacity at the 75 °C column carries the breaker rating — with the small-conductor rule applied, which caps 14, 12 and 10 AWG below their table ampacity regardless of what the table says.

The recommended conductor is the smallest gauge that also keeps voltage drop within 3% over your run. Past roughly sixty feet this is usually one size larger than ampacity alone would suggest, andthat is what most tables miss.

What this does not tell you

Three things, and each of them can change the answer:

Whether your panel can feed the circuit at all. That is a load calculation, and it is a separate question —a free breaker slot is not spare capacity.
Termination temperature ratings. This assumes the 75 °C column. Equipment listed only for 60 °C drags the whole circuit down to a lower rating.
Ambient temperature and conduit fill. A hot attic or several current-carrying conductors sharing a conduit both derate the cable.

So treat the output as what to expect, and as a way to read a quote critically — not as a specification. The conductor on your wall has to be chosen by the licensed electrician who signs for it, andthe inspector checks their arithmetic, not this page's.

Figures assume 240 V split-phase, the 75 °C ampacity column, and the 3% branch-circuit voltage-drop recommendation. US practice; not applicable to 230 V/50 Hz supplies.