Pregnancy Due Date Calculator 2026 — Find Your EDD

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Pregnancy Due Date Calculator

EDD · Weeks Pregnant · Milestones

Calculate by

Last Period

Conception Date

IVF Transfer

First day of last menstrual period

Average cycle length affects EDD

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How Your Due Date Is Calculated

The standard method (Naegele's Rule) adds 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14. For cycles longer or shorter than 28 days, the EDD is adjusted accordingly — that's why this calculator asks for your cycle length.

Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after the EDD. The due date is best understood as the center of a 5-week window (weeks 38–42) during which most full-term births occur.

First Trimester (Weeks 1–13)

Organ development, morning sickness, fatigue. Key appointments: first prenatal visit (8–10 weeks), NIPT or first trimester screening (10–13 weeks), nuchal translucency ultrasound. Miscarriage risk highest in this trimester — drops significantly after week 10.

Second Trimester (Weeks 14–26)

Often called the "golden trimester" — energy returns, morning sickness fades. Key: anatomy scan (18–22 weeks) where gender can be revealed and organ development is assessed. Baby begins to move (quickening) typically around weeks 16–22 for first-time mothers.

Third Trimester (Weeks 27–40)

Rapid weight gain, preparation for birth. Key appointments: glucose screening (24–28 weeks), Group B Strep test (35–37 weeks), weekly visits after week 36. Baby is considered full term at 39 weeks, early term at 37–38 weeks.

IVF Due Date Calculation

For Day 5 blastocyst transfers: add 261 days to transfer date (266 days minus 5 days for embryo age). For Day 3 transfers: add 263 days. IVF pregnancies are typically monitored more closely and have more precise conception dates than natural pregnancies.

Frequently Asked Questions

How is the pregnancy due date calculated?+

The standard method is Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a standard 28-day cycle and ovulation at day 14. For cycles different from 28 days, the EDD is adjusted — longer cycles push the due date later, shorter cycles move it earlier. Your healthcare provider may also adjust the due date based on early ultrasound measurements, which are considered most accurate for dating between 8–12 weeks of pregnancy.

How accurate is the pregnancy due date calculator?+

A due date calculated from LMP is accurate to within about 1–2 weeks for women with regular cycles. An ultrasound at 8–12 weeks provides more accurate dating — typically within 5–7 days. Only about 5% of babies are born on their exact due date. Statistically, most births occur in a window of ±10 days around the EDD. If your ultrasound dating differs from LMP dating by more than a week, providers typically use the ultrasound date as the official EDD.

What is considered full term in pregnancy?+

Pregnancy timing categories: Early term — 37–38 weeks 6 days; Full term — 39–40 weeks 6 days; Late term — 41 weeks to 41 weeks 6 days; Post term — 42 weeks or beyond. Babies born at 39–40 weeks have the best outcomes. Early term babies (37–38 weeks) may need extra support with feeding and temperature regulation. Most providers consider induction or delivery after 41–42 weeks depending on individual circumstances.

When will I start showing during pregnancy?+

Most first-time mothers begin to show between 12–16 weeks, when the uterus grows above the pelvic bone. Women who have been pregnant before often show earlier (10–12 weeks) because the uterine muscles are more relaxed. Factors affecting when you show: body type, abdominal muscle tone, baby's position, and whether it's a first or subsequent pregnancy. A visible "bump" that others notice typically appears between 16–20 weeks for most women.

When should I schedule my first prenatal appointment?+

Schedule your first prenatal appointment as soon as your pregnancy is confirmed, ideally for when you'll be 8–10 weeks pregnant. Some practices schedule earlier (6–8 weeks) for a viability ultrasound, especially for IVF pregnancies or those with previous pregnancy complications. At the first appointment: confirm the pregnancy and due date via ultrasound, blood tests (blood type, CBC, STIs, immunity), genetic counseling options, and prenatal vitamin guidance (400–800mcg folic acid daily).

What is the anatomy scan and when is it done?+

The anatomy scan (also called the 20-week scan or mid-pregnancy ultrasound) is typically performed between 18–22 weeks. It checks: fetal size and growth, organ development (heart, brain, spine, kidneys), placenta position, amniotic fluid levels, and cervical length. Many parents learn the baby's sex at this scan if desired. It's the most comprehensive ultrasound of the pregnancy and can identify structural abnormalities. Some findings may require follow-up imaging or specialist consultation.

How is an IVF due date calculated differently?+

IVF due dates are calculated from the embryo transfer date. For a Day 5 blastocyst transfer: add 261 days (because the embryo is already 5 days old, you subtract 5 from the standard 266-day conception-to-birth period). For a Day 3 transfer: add 263 days. These calculations are more precise than LMP-based dating because the conception date is known exactly. IVF pregnancies are dated from a "virtual LMP" — the equivalent LMP date that would produce the same due date.

What prenatal vitamins should I take during pregnancy?+

Key prenatal nutrients: Folic acid (400–800mcg) — reduces neural tube defect risk, ideally started before conception; Iron (27mg) — supports increased blood volume; Calcium (1,000mg) — bone development; Vitamin D (600 IU) — calcium absorption and immune function; DHA/Omega-3 (200–300mg) — brain and eye development. Most prenatal vitamins contain these in appropriate amounts. Start taking prenatal vitamins as soon as you're trying to conceive — neural tube closure occurs at 3–4 weeks, often before a missed period.

What does it mean to be "overdue" and when is labor induced?+

A pregnancy is considered post-term at 42 weeks (294 days). Between 41–42 weeks (late term), providers typically increase monitoring and discuss induction. Most US providers recommend induction by 41–42 weeks due to increased risks of placental insufficiency and meconium aspiration. The ARRIVE trial (2018) found that elective induction at 39 weeks did not increase cesarean rates and may have slight benefits. Your provider's recommendation for induction depends on your specific circumstances, cervical readiness, and baby's position.

Can the due date change after an ultrasound?+

Yes — your due date may be adjusted after an early ultrasound. If the ultrasound-based dating differs from LMP dating by more than 7 days in the first trimester (or more than 10–14 days in the second trimester), providers typically revise the EDD to match the ultrasound. This is most common when periods are irregular, when the LMP date is uncertain, or when there's a discrepancy between estimated and actual fetal size. After 20 weeks, ultrasound dating becomes less accurate and providers are less likely to change an established EDD.