Ovulation Calculator: Find Your Fertile Days
Enter the first day of your last period and your usual cycle length to see your most fertile days, your ovulation date and when to take a pregnancy test.
Your next fertile window
Estimated ovulation
Pregnancy test from
The day your period is due
| Cycle | Fertile window | Ovulation | Next period |
|---|
These dates are estimates based on a regular cycle. Ovulation can move by a few days from month to month, especially with PCOS, thyroid problems, stress or after delivery. Do not use this calculator as birth control. If you have been trying for 12 months (or 6 months if you are over 35), see a gynaecologist.
Written by Dn. Aruba Rashid, certified dietitian (BS Human Nutrition and Dietetics). Updated October 2026.
How to Use the Ovulation Calculator
Enter the first day of your last period, your usual cycle length and how many days your period lasts. Your cycle length is the number of days from the first day of one period to the first day of the next. If you are not sure, count back over your last 3 cycles and take the average.
The calculator shows your next fertile window, your estimated ovulation day, a calendar of your fertile days, and the dates for your next 3 cycles. It also tells you the earliest day to take a home pregnancy test.
When Do You Ovulate?
Ovulation is when one of your ovaries releases an egg. It usually happens about 14 days before your next period, not always on day 14 of your cycle. That is why your cycle length matters:
| Cycle length | Likely ovulation day | Fertile window |
|---|---|---|
| 24 days | Day 10 | Days 5 to 11 |
| 28 days | Day 14 | Days 9 to 15 |
| 30 days | Day 16 | Days 11 to 17 |
| 32 days | Day 18 | Days 13 to 19 |
| 35 days | Day 21 | Days 16 to 22 |
What Is the Fertile Window?
Sperm can live inside the body for up to 5 days, but an egg lives for only about 12 to 24 hours after ovulation. So your fertile window is the 5 days before ovulation, the day of ovulation and the day after. Your best chance of getting pregnant is in the 2 to 3 days up to and including ovulation.
For couples trying to conceive, having intercourse every 1 to 2 days during the fertile window gives the best chance. You do not need to time it to the exact hour.
Signs That You Are Ovulating
A calculator gives you an estimate. These body signs can help you confirm it:
- Cervical mucus becomes clear, slippery and stretchy, like raw egg white.
- Ovulation test kits (LH strips) from the pharmacy turn positive 24 to 36 hours before ovulation.
- Basal body temperature rises slightly, by about 0.3°C, after ovulation.
- Mild pain on one side of the lower abdomen for a few hours.
- Higher sex drive and breast tenderness in some women.
Want a Diet Plan Made Just for You?
General plans are a good start, but your body, routine and health are unique. Dn. Aruba Rashid, certified dietitian, can create a personal plan for you online, anywhere in Pakistan.
Diet Tips to Support Fertility
What you eat cannot guarantee a pregnancy, but a healthy diet and a healthy weight improve ovulation, especially for women with PCOS.
- Reach a healthy weight: for women who are overweight, losing even 5 to 10% of body weight can make periods and ovulation more regular. Check where you are with our BMI calculator.
- Cut down on sugar and maida: cold drinks, mithai, bakery items and white bread raise insulin, which can disturb ovulation.
- Eat protein and fibre at every meal: daal, chana, eggs, chicken, fish, dahi, sabzi and whole wheat roti.
- Get enough folate and iron: palak, methi, daal, chana and oranges. Start a folic acid tablet when you begin trying, as your doctor advises.
- Limit caffeine: keep chai and coffee to 2 to 3 cups a day.
If you have PCOS, our PCOS diet plan shows exactly what to eat to keep blood sugar and insulin steady.
Irregular Periods and PCOS
If your cycles vary by more than 7 to 9 days from month to month, a calendar method is not reliable. This is common with PCOS, thyroid problems, high stress, breastfeeding and after stopping birth control pills. Ovulation test kits and tracking your cervical mucus work better, and a gynaecologist can check whether you are ovulating at all.
Frequently Asked Questions
How accurate is an ovulation calculator?
It is a good starting point for women with regular cycles, but ovulation can move by a few days from month to month. Use it together with ovulation test kits or body signs for the best accuracy.
Can I get pregnant right after my period?
It is less likely, but possible if you have a short cycle, because sperm can survive for up to 5 days. With a 21 to 24 day cycle, your fertile window can start just after your period ends.
Can I use this calculator to avoid pregnancy?
No. Calendar methods are not reliable as birth control, because ovulation can change without warning. Speak to a doctor about contraception.
When should I take a pregnancy test?
The most reliable time is from the day your period is due. Testing earlier can give a false negative because the pregnancy hormone may not be high enough yet.
How long does it take to get pregnant?
Most healthy couples conceive within 12 months of trying. If you are under 35 and have been trying for a year, or over 35 and trying for 6 months, see a gynaecologist. See a doctor sooner if your periods are very irregular or absent.
Does PCOS stop ovulation?
PCOS can make ovulation irregular or stop it in some cycles, but many women with PCOS do get pregnant. Weight loss, a low sugar diet and medical treatment can help you ovulate more regularly.
Get Help with Your Fertility Diet
Dn. Aruba Rashid, a certified dietitian, creates diet plans for PCOS, weight loss before pregnancy and healthy pre-conception eating. She sees women in person in Multan, and offers video sessions for women and WhatsApp consultations across Pakistan. Once you are pregnant, use our pregnancy calculator to find your due date.