According to USA Fibroid Centers, there isn’t a strict size of fibroid is normal, but many fall in a mid-range size that often doesn’t immediately require treatment. Most fibroids measure between 5 cm and 10 cm in diameter, roughly the size of a plum to an orange, and this range is often considered typical or average for diagnosed fibroids. Fibroids can be much smaller (about 1–5 cm) with few or no symptoms, or larger than 10 cm, causing pressure and discomfort.