For a true natty, a forearm circumference of 14 inches is incredibly impressive. Considering that elite fitness competitors were found to have an average forearm girth of just 11.7 inches, you're in the top 1% of the lifting population if you have unflexed 14 inch forearms.

What size forearms are considered big?

The research is clear. If you have 13 inch forearms, then your size is well above average, which is right around 9.5” for women and 11 inches for men. The catch is that many people who're into training like to measure their forearm anatomy while it's flexed.

Is a 15 inch forearm big?

And while 15 inch upper arms certainly won't turn heads in the street in a world where everyone seems to live in the gym, 15 inch forearm muscles definitely will. Not only are forearms of this size impressive from a bodybuilding perspective, but they're impressive—intimidating even—to virtually anyone who sees them.