Estimate your baby's due date, current pregnancy week and trimester dates from your last period and cycle length. Free and private, nothing is stored.
The Pregnancy Due Date Calculator estimates your baby's due date, current pregnancy week and trimester boundaries based on the first day of your last menstrual period and your typical cycle length. It uses Naegele's rule, the standard clinical method for estimating a due date from LMP, and adjusts for cycle lengths that are shorter or longer than the typical 28 days.
Enter your last period date and cycle length, and the calculator instantly returns the estimated due date, how many weeks and days pregnant you currently are, and the approximate dates each trimester begins. Everything is calculated locally in the browser, with nothing entered stored or transmitted, which matters for such personal information.
The estimate is based on Naegele's rule, the same method commonly used by midwives and doctors as a starting point for due dates, giving a familiar and comparable result to what you may be told at an appointment.
Rather than assuming everyone has a standard 28-day cycle, the calculator lets you enter your own typical cycle length, which shifts the estimated ovulation and due date to better reflect your situation.
Because the calculation runs entirely in the browser, no personal dates or pregnancy information are sent to or stored on any server.
Naegele's rule adds 280 days (40 weeks) to the first day of the last menstrual period to estimate the due date, then adjusts slightly if your cycle length differs from the standard 28 days, since ovulation timing shifts with cycle length. This is the same starting-point method most clinicians use before an ultrasound offers a more precise estimate.
Only a small percentage of babies are born on their exact calculated due date; most arrive within a window of a couple of weeks either side. An early dating scan, which measures the foetus directly, is generally considered more accurate than an LMP-based calculation alone, particularly for people with irregular cycles.
Pregnancy is commonly divided into three trimesters: roughly weeks 1-13, weeks 14-27, and week 28 to birth. These boundaries are approximate guides used for describing typical development stages and are not fixed medical thresholds that change at an exact day.
It uses Naegele's rule: 280 days from the first day of your last menstrual period, adjusted for cycles that are longer or shorter than 28 days.
Only about 4% of babies arrive exactly on the estimated date; most births happen within two weeks either side. An early ultrasound gives the most accurate dating.
Yes. Pregnancy Due Date Calculator on Klipza is completely free with no account, no subscription and no watermark on your files, and there is no daily usage limit.
Processing happens locally in your browser wherever technically possible, so your files are not uploaded to a server, stored or shared with third parties.
Yes. It is fully responsive and runs in any modern browser on Android, iPhone, iPad, Windows and macOS — nothing to install.