When do I ovulate on a 35-day cycle?
Ovulation usually happens about 14 days before the next period starts. On a 35-day cycle, the next period starts on day 36, so ovulation is most likely around day 21 (counting the first day of your period as day 1). A 35-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 35-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 16 to 21. The best days to try are days 19 to 21.
| Cycle day | Fertility |
|---|---|
| Day 14 | Low chance |
| Day 15 | Low chance |
| Day 16 | Fertile |
| Day 17 | Fertile |
| Day 18 | Fertile |
| Day 19 | Most fertile |
| Day 20 | Most fertile |
| Day 21 | Ovulation (most fertile) |
| Day 22 | Fertility falls quickly |
| Day 23 | Fertility falls quickly |
| Day 24 | Fertility falls quickly |
Does my period length matter?
No — whether your period lasts 3, 5 or 7 days, ovulation on a 35-day cycle is still around day 21. With a 5-day period, that is about 16 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 35-day cycle could be anywhere from about day 19 to day 23. 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
32-day cycle · 33-day cycle · 34-day cycle · 36-day cycle · 37-day cycle · 38-day cycle