Ovulation Calculator

Professional ovulation predictor: supports menstrual cycle, BBT, cervical mucus, OPK and ultrasound monitoring. Smart fertile-window & intercourse-timing guidance to help you conceive naturally.

Calculate Ovulation Features

Accurate Ovulation Prediction

Choose your prediction method and enter your details to get the most accurate ovulation day & professional guidance

Default 28 days, 21-45 days is normal
Bleeding days
Affects result interpretation
Select the first bleeding day
Affects prediction accuracy
Temperature before getting up
For comparison
BBT Method Note

BBT rises 0.3-0.5 ℃ after ovulation. Continuous recording for ≥3 months is recommended.

Egg-white mucus means ovulation soon
High soft cervix means ovulation close
Cervical Mucus Note

At ovulation cervical mucus becomes clear, slippery and stretchy like egg-white.

Strong positive = ovulation in 24-48 h
Same time daily is recommended
Important

After OPK peak ovulation occurs in 24-48 h. Have intercourse tonight. Test between 2-8 pm, avoid first-morning urine.

≥18 mm = mature follicle
8-12 mm best for implantation
Ultrasound Note

Ultrasound is the most accurate method, showing follicle growth and exact ovulation time.

Days from ovulation to period
One-sided pelvic pain
Caused by progesterone after ovulation

Comparison of 5 Ovulation Prediction Methods

Learn the pros & cons of each method and pick the one that suits you best

Menstrual-Cycle Method
Accuracy:
60%
  • Simple, no equipment
  • Good for regular cycles
  • Poor for irregular cycles
  • Can't pinpoint exact day
Best for: Regular cycles
Basal-Body-Temperature
Accuracy:
75%
  • Confirms ovulation occurred
  • Low cost—only thermometer
  • Needs ≥3 months of data
  • Can't predict in advance
Best for: Patient long-term recorders
Cervical-Mucus Method
Accuracy:
65%
  • Natural & cost-free
  • Can predict days ahead
  • Requires learning & practice
  • Subjective
Best for: Willing to learn body signs
OPK / LH Strips
Accuracy:
85%
  • 24-48 h advance warning
  • Easy & objective
  • Daily testing needed
  • Small cost
Best for: TTC first choice
Ultrasound Monitoring
Accuracy:
95%
  • Most accurate method
  • See follicle growth live
  • Needs professional equipment
  • Higher cost
Best for: IVF or difficult TTC
Pro Advice

Use 2-3 methods together for higher accuracy. Menstrual-cycle + OPK is the most economical combo.

Ovulation Science

What Is Ovulation Day?

Ovulation day is the calendar day on which an egg is released from the ovary, usually about 14 days before the next period. It is the most fertile 24 hours of the cycle.

Ovulation is a precise hormonal process. Conception is most likely if intercourse occurs within the 24-48 h window around ovulation, with monthly chances of 20-25%.

Key Facts
  • Egg survives only 12-24 h
  • Sperm survives 2-3 days
  • Best intercourse: 1-2 days before ovulation
  • Monthly conception rate ≈ 20-25%

How to Calculate Ovulation Day Accurately?

Master scientific prediction and boost conception success

Menstrual-Cycle Method

Good for regular cycles; predicts by cycle length

Principle: Ovulation ≈ 14 days before next period

Formula: Ovulation day = LMP + (cycle length − 14)

Accuracy: 60% (80% if very regular)

BBT Method

Confirms ovulation by temperature shift

Principle: Progesterone raises BBT 0.3-0.5 ℃ after ovulation

How: Take temperature every morning before getting up

Accuracy: 75% (needs ≥3 months of data)

Cervical-Mucus Method

Observe discharge changes—natural & free

Principle: Mucus becomes clear, slippery, stretchy

Sign: Egg-white mucus stretches 5-10 cm

Accuracy: 65% (needs learning)

OPK / LH Strips

Detects LH surge 24-48 h in advance

Principle: LH peak appears 24-48 h before ovulation

Usage: Test daily from cycle day 10

Accuracy: 85% (easy & objective)

Ultrasound Monitoring

Most accurate medical method

Principle: Scan follicle size & growth directly

Index: Follicle ≥18 mm = mature & ready

Accuracy: 95% (most precise)

Pro Advice

Combine 2-3 methods for higher accuracy

Recommended combos:

  • Menstrual-cycle + OPK
  • BBT + Cervical-mucus
  • Ultrasound + OPK

Ovulation-Symptom Recognition Guide

Physical Signs
  • Cervical-mucus change: Clear, slippery, stretchy (egg-white)
  • BBT rise: 0.3-0.5 ℃ after ovulation
  • Mittelschmerz: Mild one-sided pelvic pain
  • Breast tenderness: Due to post-ovulation progesterone
Behavioural Changes
  • Increased libido: Natural fertile instinct
  • Heightened smell: More sensitive to certain scents
  • Skin glow: Smoother, clearer complexion
  • Mood swings: More emotional or sensitive
Reminder

About 20% of women feel almost no ovulation signs. Combine several methods for best accuracy.

Best Timing for Conception

Fertile Window

From 5 days before ovulation to 1 day after—6 days total. Intercourse during this window gives the highest chance of pregnancy.

Prime Intercourse Days

1-2 days before ovulation is ideal because:

  • Sperm survives 2-3 days and can wait for the egg
  • The egg survives only 12-24 hours after release
  • Intercourse after ovulation may miss the chance
Conception Probability
1 day before ovulation: 35%
Ovulation day: 30%
2 days before: 25%
Other days: <10%

Common Ovulation-Calculation Questions

Q: My cycle is irregular—what should I do?

A: Use OPK or ultrasound monitoring plus BBT. Record 3-6 months to find your personal pattern.

Q: How long after an OPK peak will I ovulate?

A: Usually 24-48 h, average 36 h. Have intercourse the day of peak and the next day.

Q: Why is my calculation different from reality?

A: Stress, illness, medication, etc. can shift ovulation. Cross-check with several methods.

Q: How long does it take to get pregnant?

A: Healthy couples have ~20-25% chance each cycle; 80% conceive within 6 months.

Q: Do we need intercourse every day?

A: No. Every other day during the fertile window is enough—too frequent may lower sperm quality.

Q: When should we see a doctor?

A: After 1 year of regular intercourse without conception (≥35 y: after 6 months).

Why Choose PreMami Ovulation Calculator?

All 5 Methods Covered

Menstrual cycle, BBT, cervical mucus, OPK and ultrasound—all mainstream ovulation-prediction methods supported

Smart & Precise

AI-powered algorithm analyses multi-source data; ovulation-day accuracy up to 95%, error ≤1 day

Personalised Cycle Management

Auto-generates personalised ovulation forecasts and intercourse advice based on your cycle characteristics and goals

Smart Reminders

Auto-reminds you of ovulation day, fertile window and next period—never miss the best conception chance

Frequently Asked Questions

Ovulation usually occurs about 14 days before the next period. For a 28-day cycle that is cycle day 14; for longer or shorter cycles it shifts accordingly. The luteal phase (ovulation to period) is relatively stable at 12-16 days.

With irregular cycles the calendar method alone is unreliable. Use OPK or ultrasound monitoring plus BBT. Record 3-6 months to identify your personal pattern.

After an LH peak (strong positive) ovulation usually occurs within 24-48 h, average 36 h. Have intercourse the day of the peak and the following day. Sperm survives 2-3 days, covering the entire fertile window.

A rise of 0.3-0.5 °C means ovulation has already occurred, not that it is about to happen. The rise is caused by increased progesterone after ovulation. BBT therefore confirms ovulation retrospectively.

The fertile window (conception window) spans 5 days before ovulation to 1 day after—6 days in total. Because sperm can survive 3-5 days and the egg about 12-24 hours. "Danger period" usually means the same fertile window for those avoiding pregnancy.

Common signs: 1) cervical mucus turns clear, slippery, stretchy (egg-white); 2) basal-body-temperature rises; 3) mild one-sided pelvic pain (mittelschmerz); 4) breast tenderness; 5) increased libido; 6) cervix higher and softer. Not every woman notices obvious signs.

The best timing is 1-2 days before ovulation. Sperm survives 2-3 days and can wait for the egg; the egg survives only about 12-24 hours after release. Start intercourse 2-3 days before predicted ovulation and continue until 1 day after.

Our calculator is based on medical standards and AI algorithms, combines multiple prediction methods, and reaches 95% accuracy. Final confirmation should rely on ultrasound monitoring or comparison of several months of data. We recommend cross-verifying with 2-3 methods.