Ovulation Calculator Ovulation Calendar When did your last period start? How long are your cycles? 14 Days 15 Days 16 Days 17 Days 18 Days 19 Days 20 Days 21 Days 22 Days 23 Days 24 Days 25 Days 26 Days 27 Days 28 Days (Average Cycle) 29 Days 30 Days 31 Days 32 Days 33 Days 34 Days 35 Days 36 Days 37 Days 38 Days 39 Days 40 Days Calculate Ovulation