Understanding the fertile window
The fertile window is the group of days in a cycle when sex may be timed around ovulation. This app estimates that window as the 5 days before estimated ovulation through ovulation day.
Learn
Use cycle estimates with context.
Clear, concise guidance for understanding fertile window estimates without turning them into medical claims or promises.
Why ovulation estimates vary
Ovulation can shift from cycle to cycle. Stress, illness, travel, changing routines, irregular cycles, and natural variation can all make a calendar estimate less exact.
Timing sex without pressure
The app suggests timing guidance to support planning, not pressure. Many couples find it more manageable to aim for intercourse every 1-2 days during the estimated fertile window where that feels right for both partners.
What irregular cycles mean for estimates
Irregular cycles can make ovulation timing less predictable. If cycles vary a lot, are very short, very long, or your usual pattern changes, treat the estimate as broad guidance and consider speaking to a GP.
When to speak to a GP
NHS guidance recommends speaking to a GP after 12 months of trying to conceive, or earlier if aged 36+, cycles are irregular, or there are known fertility concerns.
How to use the app responsibly
Use the calculator as an educational planning tool. Do not use it for contraception, diagnosis, confirming ovulation, or deciding whether medical care is needed.