Ovulation Calculator
Estimate your ovulation date and fertile window from your last period and cycle length.
- Estimated ovulationAug 2, 2026
- Fertile window opensJul 28, 2026
- Fertile window closesAug 3, 2026
- Next period expectedAug 16, 2026
Inputs used
- First day of last periodJul 19, 2026
- Average cycle length28 days
About this calculator
Ovulation typically happens about 14 days before the next period starts — not 14 days after the last one, which is why cycle length matters. The calculator takes the first day of your last period, adds your average cycle length, and counts back 14 days.
The fertile window spans roughly the five days before ovulation through the day after, because sperm can survive several days while the egg lives about one. If you're trying to conceive, the two or three days leading up to ovulation matter most.
Real cycles vary — stress, illness and travel all shift ovulation, and calendar estimates are least reliable for irregular cycles. Ovulation predictor kits or temperature tracking are more accurate. This is a general estimate, not contraception or medical advice.
Results are informational only — not financial, medical or legal advice.