Ovulation Calculator
Enter two details — get your complete fertility picture instantly.
Enter the very first day of bleeding
Typical: 22–45 days. Not sure? Use 28.
▶ Advanced: Set your luteal phase length
Most women: 12–14 days. If you know yours, enter it here for greater accuracy.
Most Fertile Days
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Day before & day of ovulation
Days Until Ovulation
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From today
Your Cycle at a Glance
Key Dates
📆 3-Month Cycle Forecast
| Cycle | Period Start | Fertile Window | Ovulation Day |
|---|
Estimates only. Actual dates may vary with cycle irregularities.
💡 Tips to Maximise Your Chances
- Have intercourse every 1–2 days throughout your fertile window
- The day before ovulation has the highest conception rate
- Use LH ovulation strips (available at any Irish chemist) to confirm your surge
- Track basal body temperature (BBT) each morning to confirm ovulation occurred
- Take folic acid (400mcg/day) — available from your local pharmacist
Could you qualify for free HSE-funded IVF?
Check HSE IVF Eligibility →HSE Public IVF Funding Checker
Ireland's public IVF scheme provides up to 3 fully-funded cycles for eligible couples. Answer 5 questions — takes under 60 seconds.
How We Calculate Your Fertile Window
We combine two medically validated methods for the most accurate possible estimate.
1. Naegele's Rule
Used for 200+ years and still the clinical gold standard. Your next period = last period + cycle length. Ovulation = next period minus luteal phase.
2. Standard Days Method
Validated in peer-reviewed research (Georgetown University, 2002). Sperm survive up to 5 days — so your fertile window opens 5 days before ovulation.
3. Custom Luteal Phase
Unlike basic calculators, we let you set your own luteal phase length (10–16 days), dramatically improving accuracy for women with non-standard cycles.
Signs You Are Ovulating — What to Look For
Basal Body Temperature Rise
Your BBT rises 0.2–0.5°C after ovulation and stays elevated. Track it every morning before getting up.
Cervical Mucus Changes
At peak fertility, discharge becomes clear, stretchy, and resembles raw egg whites — this is your most fertile sign.
LH Surge (Ovulation Strips)
LH surges 24–48 hours before ovulation. Use strips from any Irish chemist (€10–20) to pinpoint your surge.
Mittelschmerz
Some women feel a mild twinge or ache on one side of the lower abdomen at ovulation — this is called Mittelschmerz (German for "middle pain").
Irish Tip: Combine Tracking with Your GP
For irregular cycles, your GP can order an AMH (Anti-Müllerian Hormone) blood test to assess your ovarian reserve, or a Day 21 progesterone test to confirm ovulation occurred. Both are available through the HSE with a GP referral.
Tools That Work Alongside the Calculator
Available at Irish pharmacies or online — these are the essentials for tracking your cycle accurately.
LH Ovulation Test Strips
Detect your LH surge 24–48 hrs before ovulation. Available from Boots, Lloyds, CarePlus, and Amazon.ie. Most accurate way to time intercourse.
View on Amazon.ie →Basal Body Temperature Thermometer
Measures to 2 decimal places — essential for BBT charting. Use every morning before getting up. Confirms ovulation happened.
View on Amazon.ie →Folic Acid 400mcg — Proceive Ireland
HSE recommends folic acid for all women trying to conceive. Proceive is Ireland's leading fertility supplement, stocked at Boots and pharmacies nationwide.
View at Boots.ie →Fertility Friend App
The gold-standard cycle tracking app. Log BBT, cervical mucus, and LH results. Used by millions worldwide, compatible with all ovulation devices.
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Ovulation & Fertility Questions
Ireland's most complete fertility FAQ — all the answers in one place.