Clomid Ovulation Calculator (Clomiphene & Letrozole Cycle Dates)
Plan a clomiphene (Clomid) or letrozole cycle: tablet days, expected ovulation window, best days for intercourse, ovulation test start, progesterone blood test and pregnancy test dates.
How it works
Last tablet = first tablet day + 4 · ovulation window = 5–10 days after the last tablet (most likely 7) · progesterone test = ovulation + 7 days · pregnancy test = ovulation + 14 days
Clomiphene citrate (Clomid) and letrozole are taken for 5 days early in the cycle — usually starting on day 2, 3, 4 or 5 — to stimulate the ovaries. Ovulation most often occurs 5 to 10 days after the last tablet, typically about a week later, so with tablets on days 5–9 ovulation falls around days 14–19. Fertility guidelines suggest intercourse every 1–2 days through that window, ovulation (LH) tests starting a couple of days after the last tablet, and a mid-luteal progesterone blood test about 7 days after ovulation to confirm the medicine worked. Your doctor may also use ultrasound follicle monitoring, which overrides these estimates.
Worked example
Your period started on October 1, 2026 and you take tablets on cycle days 5–9 (October 5–9, 2026). Ovulation is most likely on cycle day 16 — October 16, 2026 — within a window of October 14–19, 2026. Start LH tests on October 11, have intercourse every 1–2 days from October 12 to 19, book the progesterone test for October 23 and take a pregnancy test on October 30, 2026 if your period has not come.
Sources: ASRM Practice Committee (2013) Use of clomiphene citrate in infertile women. Fertil Steril 100(2):341–348 · NICE CG156: Fertility problems — assessment and treatment
Frequently asked questions
When do you ovulate on Clomid?
Most women ovulate 5 to 10 days after the last Clomid tablet, typically around 7 days. With tablets on days 5–9 that is around cycle days 14–19; with days 3–7, around days 12–17.
When should I start ovulation tests on Clomid?
Start LH (ovulation) tests 1–3 days after your last tablet and test once or twice a day until you get a positive result. Clomid itself does not cause a false positive once you have stopped taking it for a couple of days.
Is letrozole timing the same as Clomid?
Yes, letrozole is also taken for 5 days early in the cycle and ovulation usually follows 5–10 days after the last tablet. Letrozole is now the first-line choice for many women with polycystic ovary syndrome.
How do I know if Clomid worked?
A progesterone blood test about 7 days after expected ovulation (around 30 nmol/L or 10 ng/mL or more), a positive LH test or ultrasound tracking show whether you ovulated. Your doctor adjusts the dose if not.
Related calculators
This calculator gives population averages for education only. It is not a method of contraception or a diagnosis — talk to your doctor, gynecologist or fertility specialist about your own situation.