Pregnancy calculator

Pregnancy Due Date Calculator

Estimate when your baby is due, how far along you are, and the key milestones of your pregnancy. Pick the method you know best — last period, conception date, or IVF embryo transfer — and we'll do the math.

Calculate based on

Typical: 28. Adjust if yours differs.

Estimated due date

Monday, 22 February 2027

279 days to go

You are about

0w 1d

pregnant — Trimester 1

Date of conception

Monday, 1 June 2026

Estimated (~2 weeks after LMP)

Key milestones

Based on your calculated EDD

  1. First prenatal visit (8–10 weeks)

    Week 9

    Monday, 20 July 2026

  2. End of first trimester

    Week 13

    Monday, 17 August 2026

  3. Anatomy scan (typically 18–22 weeks)

    Week 20

    Monday, 5 October 2026

  4. Glucose screening (24–28 weeks)

    Week 26

    Monday, 16 November 2026

  5. Third-trimester begins

    Week 28

    Monday, 30 November 2026

  6. Group B Strep test (35–37 weeks)

    Week 36

    Monday, 25 January 2027

  7. Full-term (37 weeks)

    Week 37

    Monday, 1 February 2027

  8. Estimated due date (40 weeks)

    Week 40

    Monday, 22 February 2027

Note: Due dates are estimates. Only about 5% of babies are born on their EDD. Most arrive within two weeks before or after. Your healthcare provider may adjust the date after an ultrasound. Read our medical disclaimer.

How the due date is calculated

The estimated due date (EDD) is your best calendar-day guess for when you'll deliver. There are three common ways to calculate it, and BumpBites supports all three.

1. Naegele's rule (from your last menstrual period)

Named for the 19th-century German obstetrician who popularized it, Naegele's rule adds 280 days — or 40 weeks — to the first day of your last menstrual period (LMP). It assumes a regular 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the calculator automatically adjusts: a 32-day cycle pushes your EDD four days later.

2. From conception date

If you can identify the day conception occurred (often the case with tracking apps or ovulation kits), the EDD is 266 days from that date. This method skips the "first two weeks" of gestational age — which by convention starts at LMP, even though sperm and egg haven't met yet.

3. From IVF embryo transfer

IVF gives the most precise dating because you know exactly when the embryo formed. We compute: EDD = transfer date + (266 − embryo age at transfer). So a Day-3 transfer adds 263 days; a Day-5 blastocyst transfer adds 261 days.

How accurate is the result?

A 2013 study published in Human Reproduction found that fewer than 5% of babies arrive exactly on their EDD. About half arrive within a 7-day window before or after; the vast majority arrive within two weeks either way. The most accurate single estimate is an early ultrasound — particularly before week 14 — because it measures fetal size directly rather than relying on memory of menstrual dates.

What your trimester means

  • First trimester (weeks 1–13): rapid development of all major organs, highest miscarriage risk, peak morning sickness for many.
  • Second trimester (weeks 14–27): energy usually returns, bump becomes visible, anatomy scan at ~20 weeks.
  • Third trimester (weeks 28–40+): rapid weight gain for baby, third-trimester scans, glucose screening, and preparation for labor.

Important milestones to expect

Once we know your EDD, we can show you when typical prenatal events happen — first prenatal visit, anatomy scan, glucose screening, and so on. Your provider's exact schedule may differ, but the dates above are a reasonable map.

What to do next

Once you have your EDD, you'll want to:

  • Schedule a first prenatal appointment if you haven't already.
  • Check the Food Safety Checker before that craving turns into a question.
  • Read up on what's happening week-by-week (full week-by-week tracker coming soon to BumpBites).
  • Save your due date to your Personal Space so we can personalize the rest of your visit.

Sources

  • ACOG Committee Opinion No. 700: Methods for Estimating the Due Date. American College of Obstetricians and Gynecologists. 2017.
  • Jukic AM, et al. Length of human pregnancy and contributors to its natural variation. Human Reproduction. 2013.
  • NICE clinical guideline CG62: Antenatal care for uncomplicated pregnancies. National Institute for Health and Care Excellence.

For our editorial process see our Methodology and Editorial Policy. This calculator is not a substitute for medical advice — read our Medical Disclaimer.

Frequently asked questions

How is the due date calculated?
We use Naegele's rule when you start from your last menstrual period (LMP): EDD = LMP + 280 days, adjusted for your cycle length. From conception date we add 266 days. From an IVF embryo transfer we add 266 minus the embryo's age in days (Day-3 transfer + 263 days; Day-5 transfer + 261 days).
How accurate is a due date calculator?
Due dates are estimates. Studies show only about 5% of babies are born on their estimated due date; most arrive within two weeks before or after. Your healthcare provider may revise the EDD after an early ultrasound, which is generally more accurate than LMP-based dates.
What if I don't remember the first day of my last period?
Use the conception-date method if you can pinpoint it (within a day or two), or wait for your first prenatal visit. The first ultrasound — especially before week 14 — gives the most accurate due date.
Does cycle length affect the due date?
Yes. Naegele's rule assumes a 28-day cycle. If your cycle is longer (say 32 days), ovulation happens later, so your EDD shifts later by about 4 days. The calculator above adjusts automatically when you change the cycle length.
Why do IVF and natural conception calculate differently?
With IVF you know exactly when the embryo was transferred and how old it was at transfer. So we count gestational age from a known fertilization point, not an estimated ovulation. That's why IVF calculations are often more precise than LMP-based ones.
When should I see my first ultrasound?
Most providers schedule an ultrasound between weeks 8 and 12. A dating ultrasound before week 14 is the most accurate way to estimate gestational age and may refine the EDD shown by this calculator.
What's the difference between 'gestational age' and 'fetal age'?
Gestational age is counted from the first day of your LMP, so when you're 'X weeks pregnant' you're talking about gestational age. Fetal age is counted from conception (about 2 weeks later). Both numbers are used by clinicians depending on context.

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