Basal Body Temperature
Your resting body temperature often dips slightly just before ovulation, then spikes (0.5–1°F) immediately after. Tracking this first thing in the morning confirms that ovulation has already happened.
Ovulation Calculator & Fertility Tracker
Pinpoint your fertile window and ovulation date with privacy-first precision. No account required—just simple, evidence-based cycle tracking.
Tracker Configuration
28 days
Short (22)Avg (28)Long (45)
Privacy First. Your tracking data is processed in-browser and never sent to any external server.
Ready to Visualize
Provide your last period start date and click Calculate to view your personalized timeline.
How to Use This Tracker
4 simple steps to validate your fertility window.
01
Enter Your Cycle Details
Enter the first day of your last period and your usual cycle length above. If you're not sure, the default 28 days is a good starting point.
02
Review Your Timeline
The calculator instantly maps your specific fertile window and estimating your exact ovulation day based on clinical standards.
03
Double-check Body Signs
Cross-reference these dates with what your body is telling you—like changes in temperature or fluid (see below) for the best accuracy.
04
Plan Your Timing
For conception, aim to have intercourse every other day during your highlighted high-fertility window.
How Our Ovulation Calculator Works
Evidence-based fertility predictions using the clinical calendar method.
Understanding the Calendar Method
Our ovulation calculator uses the clinical calendar method (also known as the rhythm method or standard days method) to predict your fertile window. This evidence-based approach combines your unique cycle history with standardized reproductive biology to identify your most fertile days each month.
The calendar method works by tracking your menstrual cycle length over time and using that data to predict when ovulation will occur. Since ovulation typically happens about 14 days before your next period begins (the luteal phase), we can work backwards from your cycle length to estimate your ovulation date and the surrounding fertile window.
Your privacy comes first. All calculations happen right here in your browser using secure code. Your personal data never leaves your device and isn't sent to any outside servers. No account needed, no data saved—just private tracking.
Our Calculation Methodology
Primary Fertile Indicators
Monitor these secondary biological markers to validate calendar predictions and identify your window in real-time.
Cervical Mucus Changes
As your fertile window opens, you'll notice cervical fluid becoming clear, slippery, and stretchy—like raw egg whites. This specific texture is nature's way of helping sperm survive and travel.
Cervical Position & Texture
During your most fertile days, the cervix tends to rise higher, feel softer (like your lips), and open slightly. After ovulation passes, it drops lower and feels firmer (like the tip of your nose).
Heightened Senses & Libido
Many women notice a sharper sense of smell or a subtle boost in energy and libido when they're most fertile. It's a biological cue that your body is ready for conception.
Mittelschmerz (Ovulation Pain)
About 1 in 5 women feel a brief twinge or cramp on one side of the lower abdomen when an egg is released. It can last a few minutes or hours and implies ovulation is happening right now.
Breast Tenderness
After ovulation, rising progesterone often causes breast sensitivity or fullness. If you feel this, it's a good sign you've successfully entered the luteal phase of your cycle.
LH Surge Detection
Luteinizing hormone (LH) surges 24–36 hours before the egg is released. Ovulation predictor kits (OPKs) detect this surge, giving you a reliable "heads up" before your peak fertile day.
Energy & Mood Shifts
You might feel more social and confident right before ovulation thanks to peak estrogen. Afterwards, progesterone can bring a calmer, more inward energy (or sometimes fatigue) as your cycle winds down.
Frequently Asked Questions
Common questions about ovulation tracking, fertility windows, and menstrual cycle predictions.
How accurate is this calculator?
We use the standard clinical calendar method, which works well for regular cycles. However, every body is unique—stress, sleep, or travel can shift your timeline. Think of this calculator as a reliable baseline, but listen to your body's signs for the full picture.
How many days after my period do I ovulate?
It's actually about when your *next* period starts. Ovulation typically happens 14 days *before* your next flow. So, in a 28-day cycle, that's day 14. If your cycle is 30 days, it's likely around day 16.
When is the best time to conceive?
Your 'fertile window' is the 5 days leading up to ovulation, plus ovulation day itself. Your best odds are actually the two days *before* ovulation, so sperm is already waiting when the egg is released.
Can I get pregnant during my period?
It's rare, but possible—especially if you have a short cycle (e.g., 21 days). Sperm can live for 5 days, so if you ovulate early, sex towards the end of your period could lead to conception.
How long does ovulation actually last?
The egg is only viable for 12–24 hours after release. But because sperm can survive inside you for up to 5 days, your 'fertile window' is about 6 days total.
Is this tool suitable for contraception?
No. This tool is designed for pregnancy planning and education only. It shouldn't be used as birth control, because it predicts based on averages, not your real-time biology. If you're avoiding pregnancy, please consult a pro.
Why does my cycle length change?
It's completely normal! The time before ovulation (follicular phase) can vary due to stress, illness, or even diet. interestingly, the time *after* ovulation (luteal phase) is usually consistent at ~14 days.
What are my actual chances each month?
For healthy couples timing it right, there's about a 20–30% chance of conceiving each cycle. It often takes a few months even when everything is perfect, so don't get discouraged if it doesn't happen immediately.
Can stress really delay ovulation?
Yes, focused stress (physical or emotional) creates cortisol, which can tell your brain to 'pause' reproductive hormones. This is a survival mechanism—your body waits for a calmer time to potentially start a pregnancy.
Should I track temperature/mucus too?
Absolutely. Calendar predictions give you the 'when', but signs like cervical mucus and temperature give you the 'what'. combining them (Symptothermal method) is the gold standard for accuracy.
What exactly is the Luteal Phase?
It's the home stretch—the time between ovulation and your next period. Your body pumps progesterone to prepare for a potential baby. If you're not pregnant, this phase ends with your period starting.
Can I track if my periods are irregular?
Yes, specifically to see if a pattern emerges over time. If your cycle varies by more than a week month-to-month, relying on biological signs (like mucus or OPKs) is better than relying solely on calendar dates.