Due Date Calculator
Free & instant — calculate using LMP, conception, IVF, or ultrasound
Why Calculate Your Due Date?
Pregnancy is an exciting journey, and one of the first questions many parents-to-be ask is “When is my baby due?” Our free pregnancy due date calculator gives you an instant answer. By entering a few simple details — like the first day of your last menstrual period and your average cycle length — our calculator applies standard medical rules to compute your estimated due date (EDD).
Knowing your due date helps you plan prenatal care, monitor fetal development, and prepare for the arrival of your little one. This calculator supports four methods — LMP, conception date, IVF/FET transfer, and ultrasound — so no matter how you track your pregnancy, we have you covered.
How Is Your Due Date Calculated?
Understanding the methods behind pregnancy dating
Last Menstrual Period (Naegele's Rule)
Add 280 days (40 weeks) to the first day of your last period. If your cycle differs from 28 days, we adjust the formula.
Use this calculator →Conception or Ovulation Date
If you know when you conceived, add 266 days (~38 weeks) to get your EDD.
Use this calculator →IVF / Embryo Transfer
Add 266 days minus the embryo's age. Day 3: +263 days. Day 5 blastocyst: +261 days.
Use this calculator →Ultrasound (CRL Dating)
Early ultrasound before 13 weeks is often the most accurate dating method using crown-rump length.
Use this calculator →How Accurate Is a Due Date?
What every expecting parent should know
A due date is only an estimate. Most pregnancies last around 40 weeks, but full-term is officially 37 weeks 0 days to 40 weeks 6 days. Delivery anywhere from 37 to 42 weeks is considered normal. Learn more →
Pregnancy Week by Week
Detailed baby development, symptoms, and tips for all 42 weeks
Explore by Trimester
Why Use Our Calculator?
Trusted by expecting parents around the world
Fast & Easy
Enter your LMP and cycle length — get your due date in under 3 seconds.
Medically Accurate
Uses Naegele's Rule and IVF protocols — same methods used by OB/GYNs worldwide.
Full Dashboard
See trimester, milestones, baby development, and planning dates.
Customizable
Handles irregular cycles, IVF, FET, conception dates, and ultrasound CRL.
Free & Private
No cost, no sign-up, no data stored. All calculations happen in your browser.
Works Everywhere
Fully optimized for phones, tablets, and desktops.
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Frequently Asked Questions
Common questions answered by our medical team