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Due Date Calculator

Calculate your estimated due date and important pregnancy milestone dates. Get accurate pregnancy timing based on your last menstrual period or conception date.

Calculate Your Due Date

Choose your calculation method:

Due Date Results

Month DD, YYYY
Estimated Due Date
(Day of Week)
XX
Weeks Pregnant
XXX
Days Until Due Date
X
Xst Trimester

Expected Delivery Window

Early Term (37-39 weeks):MMM DD - MMM DD
Full Term (39-41 weeks):MMM DD - MMM DD
Late Term (41-42 weeks):MMM DD - MMM DD

How Due Dates Are Calculated

Due dates are calculated by adding 280 days (40 weeks) to the first day of your last menstrual period. This method, known as Naegele's Rule, is the standard used by healthcare providers worldwide.

  • • LMP + 280 days = Estimated Due Date
  • • Only about 5% of babies are born on their due date
  • • Full term is 37-42 weeks
  • • Most babies are born within 2 weeks of due date

Understanding Your Due Date

Your due date is an estimate, not a deadline. It gives you and your healthcare team a target for planning and monitoring your pregnancy.

Early Term (37-39 weeks)
Baby is developed but may benefit from a few more weeks
Full Term (39-41 weeks)
Optimal time for delivery
Late Term (41-42 weeks)
May require additional monitoring

Factors That Can Affect Your Due Date

More Accurate Dating Methods

  • • Early ultrasound (before 20 weeks)
  • • Known conception date (IVF pregnancies)
  • • Regular menstrual cycles
  • • Accurate LMP recall

Factors That May Vary Timing

  • • Irregular menstrual cycles
  • • First pregnancy (tend to go longer)
  • • Previous pregnancy history
  • • Multiple pregnancies (twins, etc.)

Frequently Asked Questions

How accurate is the due date calculator?

The calculator is very accurate when using your LMP date, with most babies born within 2 weeks of the calculated due date. Early ultrasounds can provide even more precise dating.

What if I don't remember my last period?

If you can't remember your LMP date accurately, your healthcare provider will use an early ultrasound to determine your due date. This is often more accurate than guessing your LMP date.

Can my due date change during pregnancy?

Yes, your due date might be adjusted based on early ultrasound measurements, especially if there's a significant difference from your LMP-based date. Changes are most commonly made in the first trimester.

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