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Due Date Calculator

Calculate your baby's estimated due date from your last menstrual period.

Your details

Results

Estimated due date
Apr 27, 2027
29w 6d remaining
Days until due
209
days remaining
Gestational age
10w 0d
Day 70 of 280
Current trimester
First trimester
Weeks 1–13
Pregnancy progress (0–40 weeks)
25% · week 10 of 40
LMP · Week 0T1 end · Oct 20, 2026T2 end · Jan 26, 2027EDD · Apr 27, 2027
Trimester schedule
TrimesterWeeksStartEndStatus
First1 – 13Jul 21, 2026Oct 20, 2026In progress
Second14 – 27Oct 21, 2026Jan 26, 2027Upcoming
Third28 – 40Jan 27, 2027Apr 27, 2027Upcoming
Method: Naegele's rule — Estimated Due Date = LMP + 280 days (40 weeks), adjusted by (cycle length − 28) days for non-average cycles. Averages only; consult your provider for clinical dating via ultrasound.

What is the Due Date Calculator?

A due date calculator estimates when your baby will be born using Naegele's rule, based on the first day of your last menstrual period. The result includes your estimated delivery date, current gestational age, and the number of weeks remaining until birth.

Due Date Calculator formula

Naegele's rule: Due Date = LMP + 280 days (equivalently, LMP + 9 months + 7 days). For cycles shorter or longer than 28 days, adjust by (cycle length − 28) days. For IVF pregnancies: Due Date = transfer date + 266 days for a day-5 embryo, or + 263 days for a day-3 embryo.

How to use the Due Date calculator

  1. 1Enter the first day of your last menstrual period.
  2. 2Optionally enter your average cycle length (defaults to 28 days).
  3. 3Click Calculate to see your estimated due date.
  4. 4Review your current gestational age and remaining weeks.

Example calculation

If your LMP was January 1 and your cycle is 28 days, your estimated due date is January 1 + 280 days = October 8. With a 30-day cycle, add 2 days for an October 10 due date.

Frequently asked questions

How is my due date calculated?
Most due dates use Naegele's rule: add 280 days (9 months + 7 days) to the first day of your last menstrual period. An early first-trimester ultrasound is even more accurate, especially for irregular cycles.
How accurate is a due date calculator?
Naegele's rule is right within about a week for women with regular 28-day cycles, but only about 5% of babies arrive on their exact due date. Most are born within two weeks of it — your provider may revise the date after an ultrasound.
Can my due date change after an ultrasound?
Yes. If an early ultrasound (especially before 12 weeks) shows a size different from your LMP-based date by more than 5–7 days, your OB-GYN may adjust the due date to match the ultrasound measurements.
What if I conceived through IVF?
For IVF, the due date is calculated from the embryo transfer date: add 266 days for a day-5 blastocyst transfer or 263 days for a day-3 embryo transfer. Tell your provider the exact transfer date and embryo age.

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