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 →Have a fertility question? Ask our free Irish AI assistant
Get instant answers about HSE IVF eligibility, ovulation, irregular periods, and fertility in Ireland — verified against HSE.ie. Available 24/7. No sign-up.
Ask a Question →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.
Proceive Fertility Supplement
Ireland's #1 fertility supplement — folic acid, CoQ10, zinc & 30+ nutrients for women trying to conceive. Nationwide delivery.
Shop at Lir Pharmacy →Revive Active Supplements
Premium Irish supplement with 26 active ingredients. Supports energy, immunity and overall health while trying to conceive.
Shop at Lir Pharmacy →Folic Acid & Prenatal Vitamins
HSE recommends 400mcg folic acid daily from 3 months before conception. Browse all prenatal vitamins from Lir Pharmacy.
Shop at Lir Pharmacy →Mother & Baby Range
Everything you need from pre-conception through pregnancy — from an Irish pharmacy delivering nationwide.
Shop at Lir Pharmacy →* Affiliate links — we may earn a small commission at no extra cost to you. This helps keep OvulationCalculator.ie free.
Ovulation & Fertility Questions
Ireland's most complete fertility FAQ — all the answers in one place.
Everything You Need in One Place
Ovulation Calculator
Fertile window & ovulation day
Cycle Tracker
Log periods, get predictions & add reminders to your calendar
Due Date Calculator
Pregnancy milestones & trimesters
AI Fertility Assistant
Ask anything about Irish fertility
HSE IVF Checker
Free IVF eligibility in 60 seconds
Free IVF Ireland Guide
HSE eligibility criteria & fertility hub locations
IVF Cost Ireland 2026
Verified clinic prices & 40% tax relief calculator
IVF Clinics Ireland
Compare every Irish fertility clinic by cost & location
Irregular Periods & Fertility
PCOS, thyroid & when to see your GP — HSE verified
Ovulation Pain & Symptoms
What's normal, what's not & when to see your GP
Your Complete Guide to IVF in Ireland 2026
Everything Irish couples need to know about fertility treatment — from checking if you qualify for free HSE-funded IVF, to comparing clinic costs and choosing the right provider.
Is IVF Free in Ireland?
Check the full HSE eligibility criteria for free IVF — age limits, BMI, residency, and the 2025 expansion allowing couples with one child to qualify.
HSE Eligibility Guide →How Much Does IVF Cost in Ireland?
Verified 2026 prices from every Irish clinic — from €3,995. Plus how to claim 20–40% tax relief and use the Drugs Payment Scheme.
IVF Cost Guide →Best IVF Clinics in Ireland
Compare every major Irish fertility clinic by cost, location, success rates and specialism — Dublin, Cork, Galway and nationwide.
Compare Clinics →🛒 Recommended by Irish Women TTC
Preparing Your Body for Conception
Trusted supplements from Lir Pharmacy — Ireland's specialist online pharmacy, delivered nationwide.
Proceive Fertility Supplement
Ireland's #1 fertility supplement — folic acid, CoQ10, zinc & 30+ nutrients for women & men TTC.
Revive Active
Premium Irish supplement with 26 active ingredients. Energy, immunity & overall health while TTC.
Folic Acid & Prenatal Vitamins
HSE recommends 400mcg folic acid daily from 3 months before conception. Browse all prenatal vitamins.
Mother & Baby Range
Everything you need from pre-conception through pregnancy — from an Irish pharmacy that delivers nationwide.
* Affiliate link — we may earn a small commission at no extra cost to you. This helps keep OvulationCalculator.ie free.