Ovulation in a 36-day cycle: day 22
A 36-day cycle is just beyond the typical 21–35-day range. Ovulation is likely around day 22, but in longer cycles it is more likely to shift from month to month.
Breastfeeding, recent hormonal contraception, stress and significant weight change can all lengthen cycles for a while.
Ovulation is usually about 14 days before the next period, so in a 36-day cycle it falls on day 22 — 8 days later than in a 28-day cycle. A 36-day cycle is longer than the usual adult range of about 21–35 days. Longer cycles usually mean ovulation happens later — and sometimes less regularly — so it is worth talking to a doctor or nurse if your cycles are regularly this long, especially if you are trying to conceive.
Your 36-day cycle, phase by phase
| Phase | Cycle days |
|---|---|
| Period (typical) | Days 1–5 |
| Follicular phase | Days 1–21 (21 days) |
| Fertile window | Days 17–23, best on days 20–22 |
| Ovulation | Day 22 |
| Luteal phase | Days 23–36 (14 days) |
Start LH ovulation tests around day 19; a positive result on day 20 or 21 points to ovulation on day 22.
If your cycle is sometimes 34 or 38 days
Few cycles are identical every month. If yours ranges between 34 and 38 days, ovulation could fall anywhere from day 20 to day 24, which widens your possible fertile days to days 15 to 25. Base the start of ovulation testing on your shortest recent cycle (day 17), and expect your period between day 35 and day 39.
| Cycle length | Ovulation | Fertile window |
|---|---|---|
| 34 days | Day 20 | Days 15–21 |
| 35 days | Day 21 | Days 16–22 |
| 36 days | Day 22 | Days 17–23 |
| 37 days | Day 23 | Days 18–24 |
| 38 days | Day 24 | Days 19–25 |
Example: a 36-day cycle starting today
| Period starts (day 1) | |
|---|---|
| Start ovulation tests (day 19) | |
| Fertile window (days 17–23) | – |
| Estimated ovulation (day 22) | |
| Next period / test day (day 37) |
Test for pregnancy from day 37 — see the Pregnancy Test Calculator for exact dates.