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Pregnancy Calculator
Calculate estimated due date and pregnancy week from last menstrual period.
Examples
See what this tool can do.
Estimate a due date
Enter your LMP to see the expected due date.
Track your week
Check your current gestational week and trimester.
Tips & tricks
Get the most out of it.
- 1The LMP method assumes a typical 28-day cycle.
- 2Your healthcare provider's dating takes precedence over any estimate.
- 3Use the milestones as a general timeline, not a medical schedule.
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About Pregnancy Calculator
What this tool does
Pregnancy Calculator estimates your due date, current gestational age, trimester and key milestones from your last menstrual period.
How to use it
- Enter the first day of your last menstrual period (LMP).
- Read the estimated due date and gestational age.
- See milestones and days remaining.
How it works
It uses the standard convention of 280 days (40 weeks) from the LMP for the estimated due date, and derives gestational age and trimester from today's date.
Important considerations
- Estimates only — an ultrasound and your clinician give the accurate dates.
- Assumes a regular cycle; irregular cycles shift the estimate.
Privacy
This tool runs entirely in your browser. Nothing you enter is uploaded to a server.
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Frequently asked questions
By adding 280 days (40 weeks) to the first day of your last menstrual period — the standard clinical convention (Naegele's rule).