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Pregnancy Due Date Calculator
Estimate your due date by Naegele's rule or conception date, with trimesters and gestational age.
Due date estimate
Due date: —
From conception: —
Gestational age: —
Trimesters: —
How to use the Pregnancy Due Date Calculator
- Choose whether to count from your last period or conception.
- Pick the date on the calendar.
- Enter your average cycle length if it is not 28 days.
Features
- Due date by Naegele's rule
- Due date from the conception date
- Trimester boundaries with dates
- Current gestational age in weeks and days
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Frequently Asked Questions
Common questions about the free online pregnancy due date calculator.
Naegele's rule adds 280 days, or 40 weeks, to the first day of your last menstrual
period to estimate the due date.
The tool shifts the period date by the difference between your cycle length and 28 days
before applying Naegele's rule.
Conception is assumed about 14 days after the last period, so the due date is 266 days after
the conception or ovulation date.
The first trimester runs to 13 weeks, the second to 27 weeks and the third from 28 weeks
until the estimated due date.
Gestational age is the days between the estimated start of the last period and today, shown
in weeks and days.
Pregnancy is dated from the last period, so the first two weeks of that cycle happen before
conception.
No. It is an estimate for general information and not medical advice, and only about four in
a hundred babies arrive on it.
No. All dates are calculated locally in your browser and nothing is uploaded, stored or
shared.
Last updated: October 10, 2026