Ovulation Calculator Ovulation Calendar When did your last period start? How long are your cycles? 14 Days15 Days16 Days17 Days18 Days19 Days20 Days21 Days22 Days23 Days24 Days25 Days26 Days27 Days28 Days (Average Cycle)29 Days30 Days31 Days32 Days33 Days34 Days35 Days36 Days37 Days38 Days39 Days40 Days Calculate Ovulation