Ovulation & period calculator

Ovulation is estimated by counting back about 14 days from the start of your next expected period, because the luteal phase (ovulation to the next period) stays fairly constant at around 14 days. So for a 28-day cycle, ovulation is around day 14; for a 32-day cycle, around day 18. The calculator above does this from the first day of your last period and your average cycle length.

The fertile window is the roughly 6 days each cycle when pregnancy is possible: the 5 days before ovulation plus the day of ovulation. Sperm can survive in the reproductive tract for up to 5 days, and the egg lives for about 24 hours after release, so the days leading up to ovulation are the most fertile.

No. Cycle-based estimates are not a reliable form of contraception. Ovulation timing shifts with stress, illness, travel, and natural cycle variation, and the fertile window can fall earlier or later than predicted. If you want to prevent pregnancy, talk to a GP about effective contraception, including the pill, long-acting reversible contraception (IUDs and implants), or other options.

It is an estimate, most useful when your cycles are regular and you know your average cycle length. Because ovulation can vary by several days from cycle to cycle, treat the fertile window as a guide rather than a precise date. People trying to conceive often combine cycle tracking with ovulation signs such as changes in cervical mucus, a small rise in basal body temperature, or ovulation predictor kits.

If your cycle length varies a lot, or is consistently shorter than 21 days or longer than 35 days, cycle-based predictions are less reliable. Irregular periods can be normal in the years after your first period and approaching menopause, but they can also point to conditions such as polycystic ovary syndrome (PCOS), thyroid problems, or perimenopause. A GP can take a history, arrange blood tests, and help find out why.

Common signs include a change in cervical mucus (clearer, wetter, and more stretchy, like raw egg white), a small rise in basal body temperature after ovulation, mild one-sided lower-tummy pain (mittelschmerz), and sometimes breast tenderness or a change in libido. Not everyone notices these, and they are not a reliable way to prevent pregnancy.

Pregnancy is most likely if you have sex in the 2 to 3 days leading up to and including ovulation, when the fertile window is at its peak. The calculator highlights your estimated fertile window for the next few cycles. If you are trying to conceive, having sex every 1 to 2 days across the fertile window gives the best chance.

A late or missed period can have many causes, including pregnancy, stress, significant weight change, intense exercise, illness, travel across time zones, thyroid conditions, PCOS, perimenopause, and some medications or contraceptives. An occasional late period is common. If your periods are frequently late, absent, or have changed pattern, it is worth a GP review, and a pregnancy test if pregnancy is possible.

General Australian guidance is to see a GP if you have not conceived after 12 months of regular unprotected sex, or after 6 months if you are 35 or older, or sooner if you have irregular periods, known reproductive conditions (such as endometriosis or PCOS), or other concerns. A GP can start initial fertility checks for both partners and refer to a specialist if needed.

Yes. A NewDoc telehealth GP can review irregular, heavy, or painful periods, discuss contraception, start the first steps of a fertility check, and arrange blood tests or ultrasound referrals where appropriate. For eligible Medicare cardholders the consultation is bulk-billed, with no out-of-pocket cost, and any eScript or referral issued during the visit is included.