Ovulation Calculator
Pinpoint your fertile window and most likely ovulation day so you know the best days to try to conceive. Just enter your last period and cycle length.
Estimates for a regular cycle. Ovulation timing varies — tracking basal body temperature or using ovulation tests gives a more personalized picture.
How it works
An egg survives for about 24 hours after ovulation, but sperm can live for up to five days inside the body. That’s why the days leading up to ovulation matter just as much as ovulation day itself. Together they make up your six-day fertile window.
How this is calculated
Ovulation is estimated about 14 days before your next period (the luteal phase is fairly constant at ~14 days), so it shifts with your cycle length.
The fertile window is the ~6 days ending on ovulation day, because sperm can survive up to about 5 days. These are estimates and don’t confirm ovulation — tests or tracking are more precise.
Last reviewed: 2026-06
Frequently asked questions
When am I most fertile? +
Your fertile window is the five days before ovulation plus ovulation day itself — six days in total. The two days before ovulation are typically the most fertile.
When do I ovulate? +
Ovulation usually happens about 14 days before your next period. On a 28-day cycle that’s around day 14, but on a 32-day cycle it’s closer to day 18. We calculate it from the cycle length you enter.
How can I confirm ovulation? +
Tracking your basal body temperature, watching for changes in cervical mucus, or using ovulation predictor kits (OPKs) gives a more personalized picture than calendar estimates alone.
Related reading
- PCOS and Fertility: What to Know When You're Trying to ConceiveA plain-language guide to PCOS and fertility — how it affects ovulation, what lifestyle changes help, your medical options, and when to see a doctor. Reassuring, not alarmist.Jun 17, 2026 · 6 min readRead more→
- The Best Time to Have Sex to ConceiveThe best time to have sex to conceive is in your fertile window — the few days before and on ovulation. Here is how to time it and how often to try.Jun 12, 2026 · 5 min readRead more→
- Cervical Mucus Through Your Cycle: A Fertility GuideWhat dry, sticky, creamy and egg-white cervical mucus mean for fertility — how to read the changes to spot your most fertile days and time sex for trying to conceive.Jun 12, 2026 · 4 min readRead more→
- Charting Basal Body Temperature: A Beginner GuideA calm, beginner-friendly guide to charting basal body temperature (BBT) — how to take it, the post-ovulation temperature shift, what your chart shows, and the limits to know.Jun 12, 2026 · 4 min readRead more→
- Subtle Ovulation Signs You Might MissThe less-obvious signs of ovulation — cervical position, a libido bump, mild one-sided cramps and breast tenderness — and how to read your fertile window with more confidence.Jun 12, 2026 · 4 min readRead more→
- How to Track Ovulation (BBT, OPKs & Cervical Mucus)Track ovulation with three simple methods — basal body temperature, ovulation predictor kits and cervical mucus — and combine them to find your fertile window.Jun 3, 2026 · 5 min readRead more→
- Basal Body Temperature: How to Chart It (and What It Tells You)Charting your basal body temperature confirms when you ovulated. Here’s how to measure BBT correctly, what the post-ovulation rise looks like, and its limits.May 30, 2026 · 5 min readRead more→
- How Long After Your Period Do You Ovulate?On a 28-day cycle you usually ovulate around day 14 — about a week after your period ends. How to find your own ovulation day, whatever your cycle length.May 30, 2026 · 5 min readRead more→
- How Long Does It Take to Get Pregnant?Most couples conceive within a year — about 8 in 10 within 12 months, and many sooner. What’s typical, what affects how long it takes, and when to seek advice.May 30, 2026 · 5 min readRead more→
- How Many Days After Ovulation Does Implantation Happen?Implantation usually happens 6–10 days after ovulation. Here’s the full timeline, the signs to watch for, and when you can take a pregnancy test.May 30, 2026 · 5 min readRead more→
- How to Use Ovulation Test Strips (OPKs)Ovulation tests detect the LH surge 24–36 hours before you ovulate. When to start testing, how to read the result, and how to time things right.May 30, 2026 · 5 min readRead more→
- Signs of Ovulation: How to Know When You’re Most FertileThe most reliable signs of ovulation — from cervical mucus to a temperature shift — and how to pinpoint your most fertile days when trying to conceive.May 30, 2026 · 5 min readRead more→
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