Ovulation calculator

Ovulation Calculator | Track Fertile Days & Get Pregnant
#1 Rated Fertility Tool

Discover Your
Golden Window

Accurately predict your ovulation calculator results to maximize conception chances. We combine your cycle history with biological standards to find your peak fertility days.

Did you know?

  • 1

    The 6-Day Window

    Sperm can live for 5 days, but the egg only lasts 24 hours. Your fertile window combines these timelines.

  • 2

    Luteal Phase Matters

    Ovulation usually happens 14 days before your next period, not necessarily in the middle of your cycle.

Days
Smart Fertility Tracking

Everything You Need to Conceive

Our algorithm combines biological standards with your unique cycle data to provide the most accurate window of opportunity.

Pinpoint Accuracy

We calculate the exact 6-day fertile window based on luteal phase logic, not just generic averages.

Cycle Forecasting

Look ahead with predictive timelines for ovulation, implantation windows, and pregnancy testing dates.

100% Private

No data is sent to servers. Your sensitive health information stays strictly in your browser.

Step-by-Step Guide

How to Use the Calculator

Maximize your chances in 3 simple steps. Consistency is key when tracking your fertility journey.

1

Log Your Dates

Enter the first day of your last period. This is “Day 1” of your cycle and the anchor for all calculations.

2

Set Cycle Length

Input your average cycle length (usually 28 days). If unsure, use 28 days as a baseline or average the last 3 months.

3

Act on the Window

The calculator highlights your 6-day fertile window. For best results, plan intimacy every other day during this period.

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Cycle Phase Cheat Sheet

Menstruation Days 1-5 (Low Fertility)
Ovulation Window Days 12-16 (Peak Fertility)
Luteal Phase Days 17-28 (Post-Ovulation)

Common Fertility Questions

How accurate is this ovulation calculator?

It uses the standard biological rule (Ovulation = Next Period – Luteal Phase). It is highly accurate for regular cycles. For irregular cycles, we recommend using this as a baseline alongside ovulation test strips.

Can I conceive a boy or girl specifically?

The “Shettles Method” suggests timing sex closer to ovulation for boys and further away for girls, but scientific evidence is mixed. The most important factor is timing sex within the fertile window to conceive at all.

What if my cycle length varies?

Enter your average cycle length from the last 3-6 months. If variation is extreme (e.g., 24 days then 40 days), consult a doctor as predicting ovulation becomes difficult mathematically.

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© 2026 FertilityPro Calculator. All rights reserved.
Disclaimer: This tool provides estimates only and is not a substitute for professional medical advice.

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