Pregnancy Calculator
Work out your estimated due date, how many weeks pregnant you are right now, and when each trimester begins - from LMP, conception date, IVF transfer or an ultrasound date.
Estimated due date
Tuesday, June 1, 2027
Current gestational age
0w 0d
Days until due date
280 days
Estimated conception
Tuesday, September 8, 2026
How to Use the Pregnancy Calculator
- Choose what you know: first day of last period (LMP), conception date, IVF transfer date, or an ultrasound date with a known gestational age.
- Enter the date (and weeks/days for ultrasound mode).
- See your due date, current gestational age, trimester boundaries and key milestone dates.
Formulas Used
Naegele's rule: due date = LMP + 280 days (40 weeks)
Conception method: due date = conception + 266 days
IVF (3-day embryo): due date = retrieval + 263 days | 5-day blastocyst: + 261 days
Frequently Asked Questions
How accurate is a due date from LMP?
Only about 5% of babies arrive exactly on their due date; it is a midpoint of a normal window from 37 to 42 weeks. First-trimester ultrasound dating is usually more precise than LMP.
Why is pregnancy dated from the last period?
Because ovulation date is rarely known precisely, obstetric convention counts 40 weeks from the LMP even though conception happens about two weeks later.
When does each trimester start?
Commonly: first trimester weeks 1-13, second trimester weeks 14-27, third trimester week 28 to birth. Some sources split slightly differently at week 13/14.
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