Ovulation Calculator
Project ovulation days and fertile windows for upcoming cycles from your last period and cycle length.
Cycle details
Counted from day 1 to the next day 1
Next estimated ovulation
Fertile window Wed, Jun 24, 2026 – Tue, Jun 30, 2026
Calendar estimates are not contraception. Irregular cycles need extra cues (symptoms, OPKs) or clinical guidance.
Next six cycles
| # | Period | Ovulation | Fertile window | Next period |
|---|---|---|---|---|
| 1 | Mon, Jun 15, 2026 – Fri, Jun 19, 2026 | Mon, Jun 29, 2026 | Wed, Jun 24, 2026 – Tue, Jun 30, 2026 | Mon, Jul 13, 2026 |
| 2 | Mon, Jul 13, 2026 – Fri, Jul 17, 2026 | Mon, Jul 27, 2026 | Wed, Jul 22, 2026 – Tue, Jul 28, 2026 | Mon, Aug 10, 2026 |
| 3 | Mon, Aug 10, 2026 – Fri, Aug 14, 2026 | Mon, Aug 24, 2026 | Wed, Aug 19, 2026 – Tue, Aug 25, 2026 | Mon, Sep 7, 2026 |
| 4 | Mon, Sep 7, 2026 – Fri, Sep 11, 2026 | Mon, Sep 21, 2026 | Wed, Sep 16, 2026 – Tue, Sep 22, 2026 | Mon, Oct 5, 2026 |
| 5 | Mon, Oct 5, 2026 – Fri, Oct 9, 2026 | Mon, Oct 19, 2026 | Wed, Oct 14, 2026 – Tue, Oct 20, 2026 | Mon, Nov 2, 2026 |
| 6 | Mon, Nov 2, 2026 – Fri, Nov 6, 2026 | Mon, Nov 16, 2026 | Wed, Nov 11, 2026 – Tue, Nov 17, 2026 | Mon, Nov 30, 2026 |
Estimate only — not medical adviceView details
These dates are calendar estimates from average cycle and pregnancy lengths. They are not a diagnosis, not contraception, and not a substitute for clinical care. Talk with a qualified clinician about your situation.
How it works
Ovulation calculators estimate when an egg is likely released based on cycle length and the start of your last period. They project fertile days around that estimate for upcoming cycles.
In a textbook 28-day cycle, ovulation often occurs near day 14—but real cycles vary. Longer cycles usually push ovulation later; shorter cycles earlier.
Sperm can survive several days in the reproductive tract, so fertile windows typically include days before ovulation as well as the ovulation day itself.
These calendars are educational approximations. They do not detect the LH surge. People trying to conceive or avoid pregnancy often add ovulation tests, cervical mucus tracking, or clinician guidance.
For period forecasting, see the Period Calculator. For peak fertile-day highlighting tied to a potential due date, see Conception.
Frequently asked questions
- How many days before ovulation can I conceive?
- Often several days, because sperm can survive before ovulation. That is why fertile windows are wider than a single day.
- What if my cycle length changes every month?
- Calendar estimates become less reliable. Tracking multiple cycles or using ovulation tests usually helps more than a single average length.
- Can this replace birth control?
- No. Calendar estimates alone are not reliable contraception. Use clinically recommended methods for pregnancy prevention.
- Do illness or stress affect ovulation?
- They can. Delayed or skipped ovulation shifts the fertile window, which a static calculator cannot foresee.
Related calculators
- Due Date CalculatorEstimate a pregnancy due date from last period, ultrasound dating, conception date, or IVF embryo transfer.
- Pregnancy CalculatorTrack gestational age, trimester, and milestone dates from LMP, due date, ultrasound, conception, or IVF.
- Period CalculatorForecast upcoming period and ovulation dates using your last period start, cycle length, and bleeding days.
- Conception CalculatorHighlight peak fertile days across cycles and show the estimated due date if conception happens that month.