Need Help: 240v in Garage?

14 gauge is 15 amp
12 gauge is 20 amp
10 gauge is 30 amp
8 gauge is 40 amp
6 gauge is 50 amp
Double pole breaker 30 amp and 10/2 wire
Black and white are hot bare is ground. Unless your area requirements are 10/3. Black and red hot white neutral Bare ground