Ovulation Calculator

Parameters

First day of last period

Cycle length (days)

Period length (days)

Cycle 1

Period28 October — 1 November

Fertile window6 November — 12 November

Ovulation day11 November

Cycle 2

Period25 November — 29 November

Fertile window4 December — 10 December

Ovulation day9 December

Cycle 3

Period23 December — 27 December

Fertile window1 January — 7 January

Ovulation day6 January

Ovulation is estimated as 14 days before cycle end. Fertile window — 5 days before and 1 day after ovulation. Accuracy is lower with irregular cycles.