Gauritanaya

Pregnancy due date calculator

Estimate your due date and how far along you are today.

Runs entirely in your browser. Nothing you type is sent anywhere.

Estimated due date—

Pregnant today
—
Days to due date
—

An early ultrasound scan is the most accurate way to date a pregnancy. If your scan gives a different date, follow your clinician’s date.

For general wellness only. These results are estimates from published formulas and guidelines, not a diagnosis or medical advice. They may not suit pregnancy, children, older adults, athletes or people with health conditions. Talk to a qualified health professional about your health. In an emergency, call your local emergency number.

How to use the pregnancy due date calculator

ACOG Committee Opinion 700: by convention the due date is 280 days after the first day of the last menstrual period. For IVF, it is 261 days after a day-5 embryo transfer or 263 days after a day-3 transfer. From a conception date, this tool adds 266 days (280 days minus the 14 days the convention assumes between the period and conception). Weeks of pregnancy are counted from the first day of the last period.

  1. Choose what you know: your last period, conception date or IVF transfer.
  2. Pick the date.
  3. Read your estimated due date and how many weeks and days pregnant you are today.

Understanding your result

The due date is an estimate at 40 weeks from the first day of your last period. Weeks are counted from that day, so at conception you are already about 2 weeks pregnant by this convention. An early ultrasound may change the date, and your clinician’s date is the one to follow.

Sources

Sources checked on 9 October 2026. Formulas and thresholds are used as published; the wording on this page is our own.

Questions

How accurate is a due date?
It is an estimate, and many babies arrive before or after it. Your clinician may change the date after an early ultrasound, which ACOG considers the most accurate way to date a pregnancy.
My cycles are longer or shorter than 28 days. Does that matter?
The 280-day convention assumes a typical cycle with ovulation about two weeks after the period starts. If your cycles are irregular or much longer or shorter, an early scan is especially useful.
Why count from my period and not conception?
The date of the last period is usually easier to know than the date of conception, so pregnancy weeks are counted from it by convention.
Is this a diagnosis?
No. It compares your numbers with published ranges for general wellness. Only a qualified health professional can assess your health, taking your history and other tests into account.

Related tools