Period Cycle Calculator

Last period date + cycle length → next 3-cycle forecast (period · ovulation · fertile window)

Last period start date

Cycle length (days)

Period duration (days)

Period

Jul 21, 2026 – Jul 25, 2026

Ovulation

Aug 4, 2026

Fertile window

Jul 30, 2026 – Aug 5, 2026

Period

Aug 18, 2026 – Aug 22, 2026

Ovulation

Sep 1, 2026

Fertile window

Aug 27, 2026 – Sep 2, 2026

Period

Sep 15, 2026 – Sep 19, 2026

Ovulation

Sep 29, 2026

Fertile window

Sep 24, 2026 – Sep 30, 2026

This is an estimate only, not medical advice.