When do I ovulate on a 33-day cycle?
Ovulation usually happens about 14 days before the next period starts. On a 33-day cycle, the next period starts on day 34, so ovulation is most likely around day 19 (counting the first day of your period as day 1). A 33-day cycle is near the edge of the typical range; cycles from about 21 to 35 days are common in adults.
Your fertile window on a 33-day cycle
Sperm can live for up to five days and an egg for about a day, so the fertile window is the five days before ovulation plus ovulation day: cycle days 14 to 19. The best days to try are days 17 to 19.
| Cycle day | Fertility |
|---|---|
| Day 12 | Low chance |
| Day 13 | Low chance |
| Day 14 | Fertile |
| Day 15 | Fertile |
| Day 16 | Fertile |
| Day 17 | Most fertile |
| Day 18 | Most fertile |
| Day 19 | Ovulation (most fertile) |
| Day 20 | Fertility falls quickly |
| Day 21 | Fertility falls quickly |
| Day 22 | Fertility falls quickly |
Does my period length matter?
No — whether your period lasts 3, 5 or 7 days, ovulation on a 33-day cycle is still around day 19. With a 5-day period, that is about 14 days after your period ends.
How sure is this?
The 14-day rule is an average: the second half of the cycle usually lasts 12 to 16 days, so ovulation on a 33-day cycle could be anywhere from about day 17 to day 21. Ovulation tests, which detect the LH surge, or temperature charting can confirm your own pattern. If your cycles vary a lot, enter your average cycle in the Ovulation Date Calculator and treat the dates as approximate.
Other cycle lengths
30-day cycle · 31-day cycle · 32-day cycle · 34-day cycle · 35-day cycle · 36-day cycle