Which is thicker, 12 or 14 gauge wire?

Twelve gauge is thicker than 14 gauge. AWG runs backwards: the smaller the number, the larger the conductor. That single fact untangles most wire-size confusion.

The size difference is about 26 percent more cross-sectional area, which is why 12 AWG is allowed 20 amps on a breaker while 14 AWG stops at 15.

Telling them apart in the field: 12-2 Romex has a yellow jacket and 14-2 is white under the modern color convention, solid 12 resists finger-bending noticeably more, and the printing on the insulation settles it for certain.

The pattern continues in both directions: 10 is thicker than 12, 16 is thinner than 14, all the way down to hair-fine 40 AWG.

The wire gauge calculator turns any AWG number into diameter, area, and ampacity instantly.