This depends on a few factors, most importantly your age, gender, and BMI. As shown above, the average size of a woman's bicep is around the 12-inch mark and for men, it is roughly 13 inches. So, 17-inch biceps would be way above average regardless of your age or gender. However, if you have a high BMI then there is a good chance the size of your biceps is more down to body fat, rather than lean muscle tissue, which is not considered healthy.