Pregnancy Due Date Calculator
Estimate your due date and current week of pregnancy from your last menstrual period.
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This due date is a tentative estimate and may not match your exact delivery date. Please consult your doctor or midwife for medical advice and confirmed dates.
Your Estimated Pregnancy Timeline
This due date is a tentative estimate and may not match your exact delivery date.
Free Pregnancy Due Date Calculator
Use this free pregnancy due date calculator to estimate your due date and current week of pregnancy based on your last menstrual period.
The result shows your estimated due date, current week of pregnancy, trimester, and days remaining. This tool uses the standard Naegele's Rule method and is for informational purposes only.
How to Use the Pregnancy Due Date Calculator
- Select the first day of your last menstrual period.
- Select your average menstrual cycle length.
- Click Calculate Due Date.
- View your estimated due date, current week, and trimester instantly.
Features
- Estimates your due date using the standard Naegele's Rule.
- Adjusts for your average cycle length.
- Shows current week of pregnancy and trimester.
- Includes print, share, and download options.
Frequently Asked Questions
How is the due date calculated?
This calculator uses Naegele's Rule, which adds 280 days (40 weeks) to the first day of your last menstrual period, adjusted for your average cycle length.
Is this due date exact?
No. This is a tentative estimate only. Only a small percentage of babies are born exactly on their estimated due date. Actual delivery dates commonly vary by two weeks in either direction.
Is this calculator free?
Yes, this pregnancy due date calculator is completely free to use with no sign-up required.
Should I use this instead of my doctor's estimate?
No. Always rely on your doctor's or midwife's estimate, especially one confirmed by ultrasound, for medical decisions. This calculator is for general informational purposes only.
Method and Sources
This calculator estimates the due date by adding 280 days (40 weeks) to the first day of the last menstrual period and adjusting for the selected cycle length. This is an estimate; ultrasound dating and clinical assessment may provide a different due date.
Research that followed pregnancies with precisely measured ovulation dates found that natural pregnancy length can vary by as much as five weeks, even between healthy pregnancies. That is why any calculated date is an estimate, not a prediction of the exact day.
Sources:
- American College of Obstetricians and Gynecologists — Methods for Estimating the Due Date
- NHS — Due Date Calculator
- Jukic AM, Baird DD, Weinberg CR, et al. Length of human pregnancy and contributors to its natural variation. Human Reproduction, 2013
Read our Calculation Methodology and medical disclaimer.
Related Calculators
Want to know your current month of pregnancy? Try our pregnancy month calculator. Prefer trimesters instead? Use the pregnancy trimester calculator. Need your exact week? See the pregnancy week calculator. Not sure when you conceived? Check the conception date calculator. Want a live countdown to your due date? Use the countdown timer. Curious about your baby's age after birth? See the baby age calculator.