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Pregnancy due date calculator

Estimate a baby's due date from the last period, conception date, IVF transfer or an ultrasound, and see how far along the pregnancy is week by week.

Estimated due dateWednesday, May 19, 2027210 days to go · based on your last period
10w 0d
Today you are10 weeks 0 days
First trimesterMonth 325% of 40 weeks
Likely conception windowAug 21 – Aug 27
Ovulation (estimated)Aug 26, 2026
2nd trimester startsNov 18, 2026
3rd trimester startsFeb 24, 2027

Milestones

  1. Pregnancy test turns positiveWeek 4 · Sep 9, 2026
    Around the first missed period, when hCG is high enough for most home tests.
  2. Heartbeat visible on ultrasoundWeeks 6–7 · Sep 23 – Oct 6, 2026
    Cardiac activity is usually seen on a transvaginal scan at about 6–7 weeks.
  3. NIPT blood screening possible· nowWeek 10 · Oct 21, 2026
    Cell-free DNA screening for chromosomal conditions can be done from 10 weeks.
  4. Dating & nuchal translucency scanWeeks 11–13 · Oct 28 – Nov 17, 2026
    First-trimester ultrasound, often combined with blood tests, between 11 and 14 weeks.
  5. Second trimester beginsWeek 14 · Nov 18, 2026
    Week 14. Nausea often eases around this time.
  6. Anatomy (anomaly) scanWeeks 18–22 · Dec 16 – Jan 19, 2027
    Detailed ultrasound of the baby's organs, usually between 18 and 22 weeks.
  7. Halfway thereWeek 20 · Dec 30, 2026
    20 weeks — the midpoint of a 40-week pregnancy.
  8. Viability milestoneWeek 24 · Jan 27, 2027
    Around 24 weeks, babies born early have a chance of survival with intensive care.
  9. Glucose screeningWeeks 24–28 · Jan 27 – Feb 24, 2027
    Test for gestational diabetes, typically between 24 and 28 weeks.
  10. Third trimester beginsWeek 28 · Feb 24, 2027
    Week 28. Antenatal visits usually become more frequent.
  11. Group B strep testWeeks 36–37 · Apr 21 – May 4, 2027
    Swab test commonly offered between 36 and 37 weeks in the US.
  12. Early termWeek 37 · Apr 28, 2027
    From 37 weeks a baby is considered early term.
  13. Full termWeek 39 · May 12, 2027
    39 weeks 0 days to 40 weeks 6 days.
  14. Due dateWeek 40 · May 19, 2027
    40 weeks. Only about 4–5% of babies arrive on their exact due date.
  15. Late termWeek 41 · May 26, 2027
    41 weeks. Your provider may discuss monitoring or induction.
  16. Post-termWeek 42 · Jun 2, 2027
    42 weeks and beyond.
This is an estimate, not medical advice
Due dates are a guide: most babies are born between 37 and 42 weeks. An early ultrasound is the most accurate way to date a pregnancy, and your midwife or doctor may adjust your due date after a scan. Always follow the advice of your healthcare provider.
How we calculate

Pregnancy is counted from the first day of the last menstrual period (LMP), about two weeks before conception. A full-term pregnancy is 40 weeks, or 280 days:

due date = LMP + 280 days + (cycle length − 28 days)
Naegele's rule, adjusted for cycle length. Cycles longer or shorter than 28 days shift ovulation, and therefore the due date.
due date = conception date + 266 days
Conception happens around day 14 of a 28-day cycle, 266 days before the due date.
due date = transfer date + 266 days − embryo age
The embryo's age is subtracted: day-3 embryo → +263 days, day-5 → +261, day-6 → +260.
due date = scan date + 280 days − gestational age at scan
Gestational age at the scan is converted to an equivalent LMP.

Trimesters: first = weeks 0–13, second = weeks 14–27, third = week 28 to birth. “Weeks + days” is the number of whole weeks since the (adjusted) LMP and the days beyond.

Runs in your browser · no uploadHow it works

How to use Pregnancy due date calculator

  1. 1

    Choose what you know

    Pick last period, conception date, IVF transfer or ultrasound — whichever date you are most sure of.

  2. 2

    Enter the date

    Add the date and, if asked, your cycle length, the embryo's age at transfer or the gestational age from your scan report.

  3. 3

    See your due date and timeline

    Read the estimated due date, your current week and trimester, and when each milestone falls; check any other date in Check progress on.

Limits and Pro

Free and unlimited. Supports cycle lengths of 20–45 days, day-3, day-5 and day-6 embryo transfers, and scan ages up to 42 weeks 6 days. It gives estimates for singleton pregnancies, not medical advice.

About Pregnancy due date calculator

This calculator estimates when your baby is due and shows how far along you are today, using the same dating rules obstetricians and midwives use. You can start from four different facts: the first day of your last menstrual period (with your usual cycle length), a known conception date, the date and embryo age of an IVF transfer, or the date of an ultrasound together with the gestational age written on the report.

The result is your estimated due date with the weekday, the number of days left, your current week and day of pregnancy, the trimester, a progress ring and the likely conception window. A timeline then lists the common prenatal milestones — when a heartbeat is usually visible, when screening tests and the anatomy scan are typically offered, the viability milestone around 24 weeks, and the early-, full- and late-term dates — each placed on the calendar for your pregnancy. You can also pick any other date to see how many weeks you will be then, which helps when planning travel, leave or a baby shower.

The calculator is for planning and curiosity. It cannot detect pregnancy, predict the actual day of birth, or replace dating by your care provider; when an early ultrasound disagrees with your period-based date, the scan date is normally the one your clinic will use.

Privacy

Pregnancy dates are sensitive, so they are handled only on this device: the due date and milestones are computed in your browser and nothing is sent to us. Your dates are not written into the page address; they are remembered in this browser's local storage until you press Reset, and a link is created only if you choose Copy link.

Features

Four dating methods

Last period with cycle length, conception, IVF day-3/5/6 transfer, or an ultrasound's gestational age.

Personal milestone timeline

Scans, screening windows, viability and term dates placed on your own calendar.

Kept on your device

Dates stay in this browser and out of the address bar.

Pregnancy due date calculator: frequently asked questions

How is a pregnancy due date calculated?
The standard method, Naegele's rule, adds 280 days — 40 weeks — to the first day of your last menstrual period, assuming a 28-day cycle with ovulation on day 14. A last period that started on January 1, 2026 gives a due date of Thursday, October 8, 2026. If your cycles are longer or shorter, the date moves by the same number of days.
How accurate is my due date?
It is an estimate. Only about 4–5% of babies are born on their due date; most arrive in the five weeks between 37 and 42 weeks. A first-trimester ultrasound that measures the baby's crown-rump length is usually accurate to within about a week, which is why clinics often confirm or adjust the period-based date at the dating scan.
My cycle isn't 28 days. Does that change the due date?
Yes. Ovulation normally happens about 14 days before the next period, so a longer cycle means later ovulation and a later due date. With a 32-day cycle, a last period starting January 1, 2026 moves the due date four days, from October 8 to October 12, 2026. Enter your average cycle length and the calculator adjusts Naegele's rule automatically.
How do I work out a due date after IVF?
Count from the transfer date and the embryo's age: due date = transfer date + 266 days − embryo age in days. A day-5 blastocyst transferred on January 20, 2026 and a day-3 embryo transferred on January 18, 2026 both give October 8, 2026. Choose IVF transfer, enter the date and pick day 3, day 5 or day 6.
How many weeks pregnant am I?
Pregnancy weeks are counted from the first day of your last period, not from conception, so you are already about two weeks along at conception. With a last period on January 1, 2026, on April 15 you are 14 weeks and 6 days pregnant — just into the second trimester, which runs from week 14 to the end of week 27.

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