Ovulation Calendar & Fertility Tracker — Free & Accurate

The Ovulation Calendar & Fertility Tracker on My Medicine Advisor helps you quickly estimate your fertile window, likely ovulation day, and next period using your recent cycle data. It works instantly in your browser—no sign-in, no data storage—and it’s designed for global use, mobile first, and medical-source aligned. Your results are estimates, but when you understand how your Ovulation Calendar & Fertility Tracker works (and combine it with ovulation signs like LH tests, basal body temperature, and cervical mucus), you can dramatically improve timing when trying to conceive.

Ovulation Calendar & Fertility Tracker

Predict your fertile window using your last period and cycle length. Instant, private, and free.

Input

Use the first day of full bleeding.
Common range is 21–35 days; enter your own average.
Typically ~14 days (varies by person).
Irregular cycles? Add up to 3 recent period start dates
We’ll average the gaps and widen the fertile window when variability is high.
Ready

Your data is processed only in your browser. No information is sent anywhere.

Predictions

Next 6 cycles

Cycle # Pred. period start Likely ovulation Fertile window Earliest sensible test*
Important: This tool estimates windows based on cycle averages and typical luteal phase length. Ovulation varies cycle-to-cycle; if trying to conceive, consider combining with LH strips, BBT, and cervical mucus tracking for precision. Seek medical advice if cycles are very irregular, postpartum, or if there’s pelvic pain, PCOS, thyroid issues, etc.

Pregnancy is most likely within a six-day window—the five days before ovulation and the day of ovulation—because sperm can survive in the reproductive tract for up to five days and an egg remains viable for ~12–24 hours after ovulation. ACOGnhs.uk

Why use an Ovulation Calendar & Fertility Tracker?

  • Clarity: Your Ovulation Calendar & Fertility Tracker translates period dates and cycle lengths into a simple timeline you can act on.
  • Speed: Instant results, plus optional .ics calendar download to remember fertile days.
  • Privacy: Runs fully on-device in your browser (no data sent to a server).
  • Adaptability: If your cycles are irregular, you can input several recent period start dates and our Ovulation Calendar & Fertility Tracker widens the fertile window to reflect variability.
  • Evidence-informed: We align the calculation with medical guidance about the fertile window and luteal phase timing. ACOGNew England Journal of Medicine

How the Ovulation Calendar & Fertility Tracker estimates your fertile days

  1. Cycle basics: Ovulation typically occurs ~10–16 days before the next period. In a 28-day cycle, that often lines up near “day 14,” but cycle length differs by person and even month-to-month. Our Ovulation Calendar & Fertility Tracker uses your actual average cycle length—not a one-size-fits-all day-14 rule. nhs.uk
  2. Luteal phase anchor: The luteal phase (from ovulation to your next period) averages around ~14 days. We let you adjust this (10–17 days) because some people have shorter or longer luteal phases, which shifts the predicted ovulation day. The tracker estimates ovulation ≈ next period – luteal days, then builds your six-day fertile window backward from that point. nhs.uk
  3. Six-day fertile window: We highlight ovulation day, the five days prior, and optionally one day after (some sources reference conception up to a day post-ovulation given egg lifespan). This reflects the well-established six-day conception window. ACOGPubMed
  4. Irregular cycles: If your recent cycle gaps vary, our Ovulation Calendar & Fertility Tracker widens the fertile window accordingly, acknowledging real-world variation (late or early ovulation happens). That makes the plan more forgiving without over-promising precision. musc.edu

Evidence snapshot: A classic prospective study found the probability of conception ranges from ~10% five days before ovulation up to ~33% on ovulation day, underscoring why timing in the days before ovulation matters most. New England Journal of Medicine

How to use the Ovulation Calendar & Fertility Tracker (step-by-step)

  1. Open the tool and enter the first day of your last period and your average cycle length.
  2. (Optional) Enter your typical period length and your assumed luteal phase (keep 14 days if unsure).
  3. (Optional, irregular cycles) Add up to three recent period start dates; the Ovulation Calendar & Fertility Tracker auto-averages and widens the fertile range if needed.
  4. Click Calculate to see:
    • Likely ovulation day
    • Fertile window (with calendar-friendly dates)
    • Estimated next period
    • Next cycles table (projections for planning)
  5. Click “Add fertile window to calendar (.ics)” to save reminders, or Copy to share dates.

For best results, combine the Ovulation Calendar & Fertility Tracker with LH ovulation tests (OPKs) (LH typically surges ~24–36 hours before ovulation), basal body temperature (BBT rises after ovulation), and cervical mucus tracking. Mayo Clinic PressMayo Clinic

Smart timing tips to accompany your Ovulation Calendar & Fertility Tracker

  • Have sex regularly in the 3–4 days before ovulation through the day after ovulation. This gives sperm time to be present and ready when ovulation happens. ACOGMayo Clinic
  • Don’t wait for a positive OPK to be your first intercourse that cycle; aim to cover the days before ovulation too, since sperm can live up to five days. ACOG
  • Expect some month-to-month drift. Even with regular cycles, ovulation doesn’t always happen on the exact same day; this is why the Ovulation Calendar & Fertility Tracker builds a window, not a single guaranteed day. nhs.uk

When to take a pregnancy test after using the tracker

Most home urine tests are more accurate from the first day of a missed period, and many experts advise waiting a few days to a week after the missed period if your first test is negative but you still suspect pregnancy. If your cycles are irregular and you’re not sure when the next period is due, test ~21 days after the last unprotected sex. nhs.ukMayo ClinicPenn Medicine

Who should be cautious about calendar-only tracking?

  • Very irregular cycles, postpartum, breastfeeding, PCOS, thyroid disorders, or after stopping hormonal contraception—your ovulation timing can be especially variable. In those cases, pair the Ovulation Calendar & Fertility Tracker with OPKs, BBT, and cervical mucus observations for stronger accuracy, and consider professional guidance. CDC

How the Ovulation Calendar & Fertility Tracker improves your planning (with examples)

  • Example A: Regular 28-day cycle, luteal 14 days
    The Ovulation Calendar & Fertility Tracker estimates ovulation around day 14, fertile window roughly day 9–14, with the next period around day 28—classic textbook timing. Still, aim for multiple days across the window, not just a single “big day.” nhs.uk
  • Example B: 32-day cycle, luteal 14 days
    Likely ovulation near day 18; the Ovulation Calendar & Fertility Tracker sets a fertile window about day 13–18. You might begin OPKs a couple of days earlier so you don’t miss an earlier-than-expected LH surge. Mayo Clinic Press
  • Example C: Irregular 26–35 day pattern
    The tracker widens your window to acknowledge uncertainty and helps you schedule more coverage (e.g., sex every 1–2 days across the window). Consider adding signs (OPKs/BBT/mucus) and discussing irregularity with a clinician if it persists. ACOG

Evidence and reassurance for your Ovulation Calendar & Fertility Tracker

  • Six-day window is real. Nearly all conceptions in healthy couples happen in the six days ending on ovulation day, with the highest probabilities in the two days before ovulation and ovulation day. PubMedNew England Journal of Medicine
  • Fertile timing ≠ exact science. Medical guidance emphasizes fertile days ~10–16 days before the next period, which is why your Ovulation Calendar & Fertility Tracker personalizes prediction by your cycle length rather than a fixed “day 14.” nhs.uk
  • Behavior beats perfection. Regular intercourse every 1–2 days across the fertile days is typically as effective as clock-watching a single moment. ACOG

Internal resources to support your journey

Use these related My Medicine Advisor tools alongside your Ovulation Calendar & Fertility Tracker for a complete plan:

Trusted external reading

For authoritative background to complement the Ovulation Calendar & Fertility Tracker, see:

FAQ: Ovulation Calendar & Fertility Tracker

The Ovulation Calendar & Fertility Tracker is for education and planning. It doesn’t diagnose conditions or replace clinical evaluation. If you have very irregular cycles, no periods, pelvic pain, or you’re concerned about fertility, speak with a licensed clinician.