WorldCalcs

Pregnancy Calculator

Estimated due date, how far along you are, trimester and every milestone — from LMP, due date, conception, ultrasound or IVF transfer.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026

Estimated due date

8 October 2026

You are approximately 28w 0d pregnant (trimester 3) · 84 days to go

70% complete

Estimated conception: 15 January 2026

MilestoneDate
First trimester ends (13w 6d)8 April 2026
Second trimester begins (14w 0d)9 April 2026
Viability — 24 weeks18 June 2026
Third trimester begins (28w 0d)16 July 2026
Full term — 37 weeks17 September 2026
Due date — 40 weeks8 October 2026

This tool provides general estimates for information only and is not medical advice. Always confirm dates and targets with your doctor or midwife. See our full disclaimer.

What a pregnancy calculator does

A pregnancy calculator turns a single reference date — your last period, a known due date, conception, an ultrasound measurement or an IVF transfer — into a full pregnancy timeline: estimated due date, current weeks and days, trimester, days to go and key milestones along the way.

How the due date is calculated

The standard method is Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). Longer or shorter cycles shift the estimate by the difference from 28 days, since ovulation and conception move with cycle length. Ultrasound dating works backwards from the gestational age measured at the scan (LMP = scan date − (weeks × 7 + days), then + 280 for the EDD). IVF dating uses the known embryo age: day-5 transfer + 261, day-3 transfer + 263.

Example

If your last period started on January 1 and your cycle is 28 days, your estimated due date is October 8 — 40 weeks later. Conception is estimated around January 15 (about two weeks after your period starts). The first trimester ends near April 8, your baby reaches the point of viability at 24 weeks around June 18, and full term (37 weeks) begins around September 17.

Related: Conception Calculator, Due Date Calculator, Ovulation Calculator, Pregnancy Weight Gain Calculator.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Pick how you want to calculate, then enter the dates. The tool returns your estimated due date, current gestational age in weeks and days, the trimester, days to go, and a table of pregnancy milestones.

All inputs are treated as calendar dates in UTC, so results are the same regardless of your time zone.

Frequently asked questions

How is my due date calculated?+

Most due dates use Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, the estimate shifts by that difference. Early-ultrasound and IVF dates are counted a little differently but land on the same 40-week timeline.

How many weeks pregnant am I?+

Pregnancy is counted in gestational weeks from the first day of your last period, which is about two weeks before conception. So at the moment of conception you are already counted as 'two weeks pregnant.' This calculator shows your current weeks and days.

Can I find my due date from the conception date?+

Yes. Add 266 days (38 weeks) to the conception or ovulation date. Conception dating skips the roughly two-week gap between your last period and ovulation.

Why does pregnancy count from my last period instead of conception?+

The first day of your last period is a date most people can observe and remember, while the exact moment of ovulation is hard to pin down. Dating from the last period gives a consistent starting point.

How accurate is an estimated due date?+

It is an estimate, not a deadline. Only about 1 in 20 babies arrive on the exact due date; most are born within two weeks either side. A dating ultrasound in the first trimester is the most accurate way to confirm it.

How are the trimesters divided?+

The first trimester runs from week 1 to the end of week 13, the second from week 14 to the end of week 27, and the third from week 28 until birth.

What does 'full term' mean?+

Full term is 39 weeks 0 days to 40 weeks 6 days. 37 to 38 weeks is called 'early term,' and 41 weeks or more is 'late term.' This tool marks 37 weeks as the point where a pregnancy is generally considered full term.

How is an IVF due date different?+

An IVF due date is counted from the embryo transfer. A day-5 (blastocyst) transfer adds 261 days; a day-3 transfer adds 263 days. Because the embryo's age is known precisely, IVF dating is very reliable.

References

  • American College of Obstetricians and Gynecologists (ACOG) — methods for estimating the estimated due date.
  • Naegele's rule — 280 days (40 weeks) from the first day of the last menstrual period.

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