Many patients ask “what is the ideal follicle size” to be able to trigger ovulation. Dr. Timmreck offers, “The maturity of an egg in the follicle is in part reflected by the follicular size; on average, the ideal follicular size is 18 to 20 millimeters or larger, depending on the type of medications used.” Helpful, trusted answers from doctors: Dr. Livingston on mature follicle size at ovulation: It would be very very rare. Unless, of course, you mistook another type of cyst for follicle. Unless, of course, you mistook another type of cyst for follicle. The ideal size of the follicle would be above 19 mm. this will have a successful ovulation.th day between 1 to 5 the ideal follicle size would be more than 10 mm to have successful ovulation. First cycle, on CD12 I had only one follicle that was 12mm, on CD14 there had been no growth and I ovulated that same day. Today is CD12, I had a scan today which showed 2x12mm follicles on one side and 1x16mm follicle on the other side. Re: How many follicles/size are typical after Clomid &How big for trigger? For my bfp cycles, I did Clomid 100mg 3-7, and the first time i had one follie at 17mm at my cd 11 ultrasound - since it was a Friday, my dr had me trigger the next morning and he did the iui 36 hours later on Sunday night at 7. When follicle scans are used with Clomid along with an HCG injection, the ideal follicle size for getting mature eggs is about 18 to 30 mm diameter at the time of the hCG injection. Ultrasound and blood testing during Clomid cycles will also show us when no mature follicles are developing in response to the medication. Follicle Development and Ovulation New Hope Fertility Center. Loading. Unsubscribe from New Hope Fertility Center? Cancel Unsubscribe. Working. Subscribe Subscribed Unsubscribe 7.6K. Loading. During ovulation, a mature egg is released from a follicle. While several follicles begin to develop each cycle, normally only one will ovulate an egg. After ovulation, the follicle turns into a While several follicles begin to develop each cycle, normally only one will ovulate an egg. Helpful, trusted answers from doctors: Dr. Honore on mature egg follicle size: It would be very very rare. Unless, of course, you mistook another type of cyst for follicle. Unless, of course, you mistook another type of cyst for follicle. a 15mm seems to be too small to indicate mature follicle. that's awesome to develope so many follicles from a 50mg clomid ,, you must be so sensitive to this medication. wish u luck and keep us posted.