Pregnancy Due Date Calculator

Q: How accurate is the due date?

It is an estimate; only about 5% of babies are born on the exact due date. Most arrive within 2 weeks before or after.

Q: What are the trimesters?

First trimester weeks 1-12, second weeks 13-26, third weeks 27-40.

Q: Can I use conception date instead?

Yes, add 266 days (38 weeks) to the conception date for a slightly more precise estimate.

Pregnancy Due Date Calculator

First Day of Last Menstrual Period

Your pregnancy due date (estimated date of delivery) is calculated from the first day of your last menstrual period. This free calculator uses Naegele’s rule — the standard method used by healthcare providers — to estimate when your baby will arrive.

How to Use This Calculator

Enter the first day of your last menstrual period (LMP).
Click Calculate Due Date.
See your estimated due date (LMP + 280 days) and likely conception date.

Naegele’s Rule:
Due Date = First day of LMP + 280 days (40 weeks)
Assumes a regular 28-day cycle. Only ~5% of babies arrive exactly on their due date.

Worked Example

LMP: January 1, 2026. Due date = Jan 1 + 280 days = October 8, 2026. Conception likely around January 15, 2026.

Our Testing Process

Every DaProfitClub calculator is tested before publishing. We verify date arithmetic against calendar calculations (including leap years and month lengths), test edge cases, and confirm the tool works on desktop and mobile browsers. Health formulas are cross-checked against medical references.

Frequently Asked Questions

How accurate is the due date?

It is an estimate. Only about 5% of babies are born on their exact due date; most arrive within 2 weeks before or after.

What if my cycles are irregular?

Naegele’s rule assumes a 28-day cycle. With irregular cycles, an early ultrasound gives a more accurate dating — ask your healthcare provider.

What are the trimesters?

First trimester: weeks 1–12. Second: weeks 13–26. Third: weeks 27–40 (delivery).

Can I use conception date instead?

Yes — add 266 days (38 weeks) to the conception date. If you know it, that can be slightly more precise.

Related Calculators

Ovulation Calculator — find your fertile window.
Age Calculator — calculate exact age.
BMR Calculator — estimate daily calorie needs.
Date Calculator — add or subtract days from any date.

Shahnawaz

Shahnawaz is the founder of DaProfitClub, a free online platform offering 100+ calculators and converters for finance, health, math, and everyday life. With a background in finance and mathematics, he designs accurate, easy-to-use tools.

Sources

American College of Obstetricians and Gynecologists (ACOG) — methods for estimating due date.
National Institutes of Health (NIH) — pregnancy dating guidance.

Disclaimer: This calculator is for educational purposes only and is not medical advice. Pregnancy dating should be confirmed by a qualified healthcare provider. If you have concerns, consult your doctor or midwife.

Last updated: September 30, 2026