Due Date Calculator

Estimate your baby's due date using Last Menstrual Period (LMP) or estimated conception date.

Only 5% of babies are born exactly on their due date. Use this as a guide only.

Calculate Your Due Date

Standard is 28 days. Adjust if your cycles are longer or shorter.

About This Due Date Calculator

Our Due Date Calculator uses the standard Naegele's Rule (LMP + 280 days) to provide a best estimate for your baby's arrival. If you only know the conception date, this tool can convert that into an expected due date as well. Keep in mind that only 5% of babies are born exactly on their due date—most births happen within two weeks either side. Your healthcare provider will refine this date with ultrasound measurements.

Use this calculator to plan prenatal appointments, checkups, and to explore the pregnancy week-by-week content on our site.

Example calculation: If LMP = Jan 1 and cycle length = 28 → due date ≈ Oct 8

Related: Baby Gender Prediction

Once you have your due date, you might be curious about your baby's gender. While the most accurate methods are medical (ultrasound and NIPT), there are several traditional methods people enjoy for fun:

Accurate Medical Methods

  • Ultrasound: 95-99% accurate at 18-20 weeks
  • NIPT: 99% accurate from 9 weeks

Traditional Methods (For Fun)

  • Nub Theory: 75% accurate at 12-14 weeks
  • Chinese Gender Chart: Based on lunar age
  • Shettles Method: Based on timing of conception

For detailed information about these methods, including accuracy rates and how they work, visit Nub Theory Gender Predictor or explore other Baby Gender Prediction Methods.

Related Tools

Ovulation Calculator

Calculate your most fertile days to increase chances of conception.
Pregnancy Week Calculator

Track your pregnancy progress week by week with important milestones.
Conception Calculator

Determine your likely conception date based on your due date or LMP.

Frequently Asked Questions

How is due date calculated?

The due date is typically calculated using Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a regular 28-day cycle with ovulation on day 14. If your cycle length differs, the calculation is adjusted accordingly.

How accurate is the due date?

The due date is an estimate. Only about 5% of babies are born on their exact due date. Most babies are born between 37 and 42 weeks of pregnancy. Ultrasound measurements, especially in the first trimester, can provide a more accurate estimate.

What if my cycles are irregular?

If your cycles are irregular, the LMP method may be less accurate. In such cases, early ultrasound measurements are typically used to determine gestational age and due date. Your healthcare provider will use the most reliable method available.

Which method is best: LMP or ultrasound?

Both methods have their place. LMP is used for initial calculations, but ultrasound measurements, especially in the first trimester, are often more accurate. If there's a significant discrepancy between the two, healthcare providers typically rely on the ultrasound dating.

Can I change cycle length?

Yes, you can adjust the cycle length in our calculator. The standard calculation assumes a 28-day cycle, but you can select a different length if your cycles are typically longer or shorter. This will adjust the estimated ovulation date and due date accordingly.