TRYING TO CONCEIVE
Use your latest period and usual cycle length for a quick estimate of likely ovulation and fertile-window dates.
Use the calculator
FREE OVULATION CALCULATOR — USE IT NOW
Enter the first day of your last period and your usual cycle length to see a one-time estimate of your ovulation date and fertile days.
This result shows your estimated fertile-window timing. For pregnancy prevention, use a recognised contraceptive method.
*The information submitted in this calculator is not stored.
Understanding your resultYour estimated fertile window is based on the cycle information entered. Cycles differ between women and can change from month to month. For pregnancy prevention, use a recognised contraceptive method.
We estimate your next period from your usual cycle length, then count back approximately 14 days for an estimated ovulation date. The fertile window shown covers the five days before ovulation through the following day.
Cycle timing can change, so one calculation is less useful than consistent tracking over several cycles.
A HELPING HAND FOR WHAT COMES NEXT
Talk through the estimate with Aura, or keep it with your dates so it is easy to find next time.
Aura can guide you through the same calculation one question at a time and help make the dates easier to understand.
Continue with AuraCreate a free ParentAura+ App account to keep this dated result, follow changes and build a clearer report over time.
Your result is still here. Please open ParentAura+ separately to continue.
WHAT YOUR ESTIMATE SHOWS
USEFUL TO KNOW
This is an estimation based on the details entered. Please consult your gynaecologist to confirm the outcome when it relates to your care.
UNDERSTANDING OVULATION
If you are trying to get pregnant, it helps to understand what ovulation means and why only a few days in each cycle are considered the fertile window.
During a menstrual cycle, hormonal changes prepare the body for a possible pregnancy. Ovulation happens when one of the ovaries releases an egg. The egg then moves into a fallopian tube, where it may meet sperm.
The egg remains available for fertilisation for a relatively short time—usually less than a day. Sperm may survive for several days, which is why pregnancy can happen after sex that took place before ovulation rather than only on the day the egg was released.
The fertile window is the part of the cycle when pregnancy is most likely. It is generally described as the five days before ovulation, the estimated ovulation day and approximately one day afterward.
An ovulation calculator gives you a practical date range for planning. Tracking cycle changes over time creates a more personal view of your timing.
The calculator uses two pieces of information:
Your cycle length is counted from the first day of one period to the day before the next period begins. The calculator estimates when the next period may start and then counts back approximately 14 days to estimate ovulation. It uses that estimated ovulation date to show a possible fertile window.
This method is simple and useful for an initial estimate, but the second half of the cycle is not exactly 14 days for every woman. Stress, illness, travel, sleep changes, breastfeeding, medication, PCOS and other factors may also affect cycle timing.
Twenty-eight days is commonly used as a reference point. Healthy menstrual cycles differ between women and can vary from month to month.
What matters is understanding your own pattern. If your periods are consistently very short, very long, frequently missed or suddenly different from your usual cycle, speak with a gynaecologist rather than relying only on a calculator.
Some women notice changes around ovulation, while others notice very subtle changes. Recording them over several cycles may help you recognise your own pattern.
Discharge may become wetter, clearer and more slippery as ovulation approaches.
Your resting temperature may rise slightly after ovulation. It is most useful when measured consistently each morning.
Urine tests detect a rise in luteinising hormone (LH), which commonly happens before ovulation.
Some women report mild pelvic discomfort, bloating, breast tenderness or a change in sexual desire.
Checking cervical position yourself is difficult and unnecessary for most women. Period dates, ovulation tests, cervical-mucus observations and basal body temperature are generally easier to record consistently.
Tracking can help identify the days when sex is more likely to result in pregnancy and make timing easier to understand.
If you use an ovulation predictor kit, begin testing shortly before the fertile window estimated by the calculator and follow the instructions supplied with the kit. Recording results over two or three cycles may provide more useful information for you and your gynaecologist.
The My Fertile Days App goes beyond a one-time estimate by keeping your cycle dates and selected tracking information together. Over three to four weeks—and ideally across more than one cycle—it can begin building a clearer record for your dashboard.
Professional support can be useful when periods are repeatedly absent or very irregular, pain or bleeding feels unusual, or you have concerns about ovulation.
General fertility guidance commonly suggests seeking an evaluation after 12 months of trying if you are younger than 35, or after six months if you are 35 or older. Earlier advice may be appropriate if you are over 40 or already know about a condition that may affect fertility.
A calculator is a starting point. A gynaecologist can consider your age, medical history, cycle pattern, medicines, test results and your partner’s health before suggesting what should happen next.
Yes. A predicted window is based on estimated ovulation, and the actual day can shift. If you are trying to conceive, regular sex every two to three days throughout the cycle can reduce the need to identify one exact day.
The ParentAura calculator can show a broader estimated window using the dates and cycle length you enter. With irregular cycles, adding several period dates and selected ovulation signs in the App creates a more useful personal pattern than relying on one calculation.
Some women notice clearer, wetter cervical mucus, a positive LH test or a small rise in basal body temperature after ovulation. Signs differ between women and may be subtle.
It uses the first day of your latest period and your usual cycle length to estimate an ovulation date and the surrounding fertile window.
The App brings together the cycle dates, fertile-window estimates and selected signs or test results you add. Comparing more than one cycle makes your own timing pattern easier to see.
A HELPING HAND FOR FUTURE DATES
The matching ParentAura+ App keeps the dates and updates you choose to add together, so your own pattern becomes easier to follow over time.
FREQUENTLY ASKED QUESTIONS
No. Every calculator gives its result without asking for an account or contact details.
No. Your entries stay in the browser while you calculate and are not automatically added to a ParentAura profile.
You can leave with the result, talk it through with Aura, or explicitly save it to a free ParentAura+ Account for ongoing tracking.
No. Calculators provide mathematical estimates and general planning information. A qualified medical professional provides diagnosis and treatment.