Ovulation & Fertility Calculator
Estimate your ovulation date and fertile window from your cycle.
Runs in your browser — files never leave your device
Ovulation
2024-01-15
Fertile from
2024-01-10
Fertile until
2024-01-16
An estimate based on cycle averages — not a contraception method.
How it works
Enter your last period’s start date and cycle length to estimate ovulation and your fertile window.
Frequently asked questions
- How is ovulation estimated?
- Roughly 14 days before your next period, with a fertile window from 5 days before to 1 day after.
- Can I use this for contraception?
- No — it’s an estimate based on averages and isn’t a reliable birth-control method.
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