An approximate date range for adults with regular natural cycles.
Starting values are an example. Replace them with your own.
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Enter your details and run the calculation.
Calendar estimate, not confirmation of ovulation. Pregnancy is possible outside the displayed dates. Do not use this tool for contraception.
Full disclaimerThe calculator adds your usual cycle length to the first day of your last period and places ovulation about 14 days before the next period. The central fertile window runs from 5 days before to 1 day after that estimate, and a wider range shows how cycle variation can shift it. It works only for regular natural cycles of 21 to 35 days without hormonal contraception. It does not confirm ovulation and pregnancy is possible outside the dates shown, so never use it as contraception and ask a gynaecologist for advice.
If your period started on 1 October 2026, the next is expected on 29 October and ovulation around 15 October. The central fertile window is 10 to 16 October, and the wider range for cycle variation is 8 to 20 October. This is a calendar estimate, so ask a gynaecologist for personal advice.
No. An ovulation calculator gives only a calendar estimate for regular natural cycles and does not confirm ovulation. Pregnancy is possible outside the dates shown, and the model is not reliable with irregular cycles or hormonal contraception. Talk to a gynaecologist about contraception and planning a pregnancy.
METHOD
Ovulation approximately 14 days before the next period. Central window: 5 days before to 1 day after. The wider range illustrates variability, not a confidence interval.
TRACEABLE