The normal testosterone level for an average adult woman is between 15 and 70 nanograms per deciliter, according to Healthline. In comparison, the average adult male has a testosterone level between 270 and 1,070 nanograms per deciliter. Testosterone levels in men and women vary with age.
Women experience a drop in estrogen levels after starting menopause, which causes an increase in testosterone, Healthline states. When a woman has too much testosterone in the body, it may cause infertility, loss of hair from the scalp, growth of facial hair or acne. If a woman does not have enough testosterone, it often results in fertility problems, fragile bones and a decrease in libido.