Calculadora de Janela Fértil Online Grátis
Calculate your exact fertile days for natural conception planning
The fertile window is the limited number of days each cycle when conception is possible. This calculator identifies your exact fertile days based on your cycle pattern, highlighting peak fertility days separately from the broader window — so you can focus timing on the highest-probability days.
Frequently Asked Questions
Sobre Esta Calculadora
A woman can only conceive during a narrow window each cycle. Sperm viability in the female reproductive tract (up to 5 days) and egg viability after ovulation (12–24 hours) define this window. Understanding it is useful both for those trying to conceive and for those practicing fertility awareness as contraception.
The calculator uses the standard formula: ovulation occurs approximately 14 days before the next expected period, regardless of cycle length. This means that in a 35-day cycle, ovulation happens around day 21 — not day 14 as it would in a 28-day cycle.
For contraception purposes, calendar-based methods alone have a relatively high failure rate (estimated 10–25% typical use per year). They work best when combined with BBT charting, cervical mucus observation, and OPK testing.
Identifique os seus dias exatos férteis para aumentar as chances de concepção.
Exemplo Resolvido
Fertile window for a 32-day cycle starting June 1
Entradas:
- LMP start: June 1, 2025
- Cycle length: 32 days
Passo a Passo:
- Estimated ovulation: June 1 + (32 − 14) = June 19
- Full fertile window: June 14 – June 20 (days 14–20 of cycle)
- Peak fertility: June 18–19 (day before + day of ovulation)
- Next period: July 3, 2025
Dicas
- Peak fertility is the 2 days around ovulation. The full fertile window spans up to 6 days.
- Use alongside ovulation predictor kits for highest accuracy.