Due Date Calculator
Find your estimated due date and track your pregnancy milestones
🤰 Calculate Your Due Date
How Your Due Date Is Calculated
Your estimated due date (EDD) represents 40 weeks from the first day of your last menstrual period (LMP). This method, called Naegele's rule, has been used since the 1800s.
The Math Behind It
From Last Period: 40 weeks (280 days) from LMP. This assumes ovulation occurred on day 14 of your cycle.
From Conception: 38 weeks (266 days) from conception/ovulation. More accurate if you know exactly when you ovulated.
From IVF Transfer: Based on embryo age at transfer, calculating back to conception equivalent.
Why Due Dates Are Estimates
Your due date is called an "estimated" due date for good reason:
- Only about 5% of babies are born on their due date
- Most babies are born within 2 weeks before or after
- First-time moms often deliver a few days past their due date
- Cycle lengths and ovulation timing vary between people
Your healthcare provider may adjust your due date based on early ultrasound measurements, which can more accurately determine gestational age.
Pregnancy Essentials
Got your due date? Here are the essentials to start your pregnancy off right:
💊 Prenatal Vitamins
Ritual Essential Prenatal
Methylated folate, choline, DHA, and vitamin D in one delayed-release capsule. Gentle on sensitive stomachs—perfect for first trimester.
- ✓ Methylfolate (not folic acid)
- ✓ Includes DHA and choline
- ✓ Delayed-release for less nausea
$35/month (subscribe & save)
Get Started →Nature Made Prenatal + DHA
Affordable, reliable prenatal from a trusted brand. USP verified for quality.
~$20-25
Check Price on Amazon →One A Day Prenatal Advanced
Complete prenatal with DHA, folic acid, and iron. Good budget option.
~$15-20
Check Price on Amazon →📚 Pregnancy Books
What to Expect When You're Expecting
The classic pregnancy guide, now in its 5th edition. Week-by-week guidance on what's happening with you and baby.
~$16-20
Check Price on Amazon →The Mama Natural Week-by-Week Guide
Natural approach to pregnancy with evidence-based information. Great for those wanting less medicalized guidance.
~$18-22
Check Price on Amazon →Expecting Better by Emily Oster
Data-driven look at pregnancy guidelines. Perfect for those who want to understand the evidence behind the rules.
~$15-18
Check Price on Amazon →Frequently Asked Questions
How accurate is this due date calculator?
This calculator uses the same method your doctor uses. However, it's most accurate if you have regular 28-day cycles. Early ultrasound (before 12 weeks) can refine your due date based on actual fetal measurements.
What if my cycles are irregular?
If you don't have 28-day cycles, the LMP method may be less accurate. If you know your ovulation date, use the conception calculator for better accuracy. Your first ultrasound will provide the most reliable date.
What's the difference between gestational age and fetal age?
Gestational age counts from your last period (about 2 weeks before conception). Fetal age counts from actual conception. When you're "8 weeks pregnant," your baby has been developing for about 6 weeks.
When should I tell my doctor I'm pregnant?
Call your doctor as soon as you get a positive test. They'll schedule your first prenatal appointment, typically between 8-10 weeks. If you have history of complications, they may want to see you sooner.
What if my doctor gives me a different due date?
Ultrasound dating, especially in the first trimester, is considered more accurate than LMP-based dating. If your dates differ by more than 5-7 days, your provider may adjust your due date based on the ultrasound.