Pregnancy Due Date Calculator
Estimate a due date, current pregnancy week, and trimester from LMP or conception date.
About the tool
What it does and what to expect
About the tool
What it does and what to expect
Estimate pregnancy timing
Expectant parents and maternity professionals use due-date estimates to plan appointments and understand pregnancy weeks and trimesters. The common LMP method counts 280 days from the first day of the last menstrual period, adjusted for cycle length.
A worked example and medical note
An LMP date of 1 January with a 28-day cycle gives an estimated due date around 8 October of the same year. Due dates are estimates; irregular cycles, assisted conception, and ultrasound dating can produce a different clinical date.
How it works
A simple, local workflow
How it works
A simple, local workflow
- 1Choose last menstrual period or conception date, enter the date, and provide cycle length when using LMP.
- 2The tool adds 280 adjusted days from LMP or 266 days from conception.
- 3It compares the estimated timeline with today to show pregnancy week, trimester, and days remaining.
FAQs
Common questions
FAQs
Common questions
How is a pregnancy due date calculated from LMP?
The standard estimate adds 280 days, or 40 weeks, to the first day of the last menstrual period and adjusts for cycle length.
Why does ultrasound show a different due date?
Ovulation timing can vary, and early ultrasound measurements may provide better clinical dating than an uncertain LMP.
How accurate is a due date?
It is an estimate rather than a guaranteed delivery date; only a small percentage of births occur on the exact estimated date.
Which trimester am I in?
This tool labels weeks below 14 as first trimester, weeks 14–27 as second, and week 28 onward as third.
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Comments & feedback
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