Pregnancy Due Date Calculator

First day of last period

Cycle length, days

Result

Estimated due date2026-10-22
Gestational age today28 нед. 1 дн.
Trimester3
Days to due date83

This result is informational only and is not professional advice.

Naegele's rule, with a correction for cycles that are not 28 days

Estimate a due date from the first day of your last period, adjusted for cycle length, plus how many weeks along you are today.

The standard method counts 280 days from the first day of the last period. It assumes a 28-day cycle with ovulation on day 14, so a longer or shorter cycle shifts the date accordingly.

Treat the result as a midpoint, not an appointment. Only about 4% of babies arrive on the estimated date, and a dating ultrasound in the first trimester is considerably more accurate than any calendar calculation.

What this calculator shows

The estimated due date
Gestational age today in weeks and days
Which trimester that falls in and how many days remain

What to keep in mind

Counts 280 days from the last period, adjusted by the difference between your cycle and 28 days.
This is an estimate for planning. Antenatal care and ultrasound dating come from your clinician, not from a web page.

FAQs

How accurate is a due date?

Roughly 4% of births happen on the exact date. Most arrive within two weeks either side, which is why 37 to 42 weeks is all considered term.

Why count from the last period rather than conception?

Because the date of the last period is usually known and the date of conception rarely is. It means the first two weeks of a pregnancy counted this way happen before conception.

What if my cycle is not 28 days?

Enter your real cycle length. A 32-day cycle typically means later ovulation, so the estimate shifts about four days later.

Should I rely on this instead of a scan?

No. A first-trimester ultrasound measures the fetus directly and is more accurate, especially with irregular cycles. Use this for a rough idea between appointments.

Worked example

A standard cycle

Input: Last period 15 January, 28-day cycle

Output: Due date around 22 October

Note: With a 32-day cycle the same start date moves the estimate four days later, since ovulation happens later in the cycle.

Useful links

All tools in Health calculators for weight, calories, macros, and BAC estimates

Pregnancy Due Date Calculator

Result

Related tools

When can I drive after drinking?

BMI Calculator

Daily Calorie Intake Calculator

Useful links