Pregnancy Calculator
Estimate your due date and see exactly how far along you are — from your last period, conception, a known due date, or an ultrasound, with your trimester and milestone dates.
From a last period of 1 January 2025, the estimated due date is Wednesday, 8 October 2025 — by 1 June you'd be 21 weeks 4 days along, with 18 weeks 3 days to go.
280 days
Naegele's rule: due date = first day of last period + 40 weeks
3 trimesters
First 0–13 weeks, second 14–27 weeks, third 28 weeks to birth
37–42 weeks
The full-term window — few babies arrive exactly on the estimated date
More than just a due date
Four input methods, your exact gestational age, and a milestone timeline.
Four ways to date it
Calculate from your last menstrual period, a known conception or ovulation date, an existing due date, or the gestational age from a dating ultrasound — whichever you have.
Know exactly how far along
See your gestational age in weeks and days, your current trimester, the percentage complete, and how many days are left until your estimated due date.
A milestone timeline
End of the first trimester, the third-trimester mark, full term and your due date are all mapped to real calendar dates so you can see what's next.
How the Pregnancy Calculator Works
Formula
Due date = last period (LMP) + 280 days (Naegele's rule, 40 weeks)
Conception = due date − 266 days (fertilization to birth)
Cycle adj. = LMP + (cycle − 14) for ovulation (default cycle 28 days)
Gestational age = today − LMP, shown as weeks + days
Days to go = due date − today
Trimester: 1st 0–13w6d · 2nd 14w0d–27w6d · 3rd 28w0d onwardPick what you know
Last period, conception, due date, or ultrasound.
Enter the date
Everything is derived from this single reference point.
Adjust your cycle
Last-period method only — fine-tunes ovulation timing.
Read your timeline
Due date, weeks along, trimester, and days remaining.
See the milestones
Key gestational weeks mapped to real calendar dates.
Every method resolves to the same internally consistent set of dates: a last menstrual period (LMP) anchor, a conception date 266 days before the due date, and a due date 280 days after the LMP. That means switching input methods never produces contradictory results.
These figures follow standard obstetric dating and are for general planning only. Pregnancy length varies, full term spans 37 to 42 weeks, and your healthcare provider's dating — especially from an early ultrasound — should always take precedence.
Frequently Asked Questions
Related Calculators
Plan the whole journey, from cycle to due date.