Free Pregnancy Due Date Calculator

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. Most pregnancies deliver within 2 weeks of the calculated date.

First trimester: weeks 1–12 (fertilization through early organ development). Second trimester: weeks 13–26 (fetal movement, anatomy scan). Third trimester: weeks 27–40+ (rapid fetal growth, birth preparation). Full term is weeks 39–40.

The EDD is an estimate — only about 5% of babies are born exactly on their due date. About 80% are born within 2 weeks before or after. Ultrasound dating in the first trimester is more accurate than LMP-based calculation.

Enter your actual cycle length for a more accurate calculation. The tool adjusts the ovulation date (day 14 of a 28-day cycle becomes day 17 of a 31-day cycle, etc.) to calculate a personalized estimated due date.

Gestational age (what doctors use) counts from LMP — typically 2 weeks before conception. Fetal age counts from conception. When a doctor says "20 weeks pregnant," that's gestational age (fetal age is ~18 weeks).

Yes, the Pregnancy Due Date Calculator on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.

Calculate your due date, current week of pregnancy, and trimester from your last menstrual period or conception date — free online pregnancy calculator. No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.

No installation needed. The Pregnancy Due Date Calculator runs entirely in your web browser on any device — desktop, tablet, or mobile.

Completely safe. The Pregnancy Due Date Calculator processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.

After the page loads for the first time, the Pregnancy Due Date Calculator works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.

The Pregnancy Due Date Calculator uses clinically validated formulas such as the Mifflin–St Jeor or Harris–Benedict equations where applicable. Results are population-based estimates and can differ from measured values by 10–20% for individuals with atypical body composition. See our <a href="/methodology/">Methodology page</a> for full formula sources and references. Consult a qualified healthcare professional before making medical or dietary decisions.

The Pregnancy Due Date Calculator uses an established, peer-reviewed formula endorsed by leading health organisations such as the WHO, CDC, or NIH where applicable. The specific formula is chosen for its validated accuracy across diverse adult populations under normal conditions.

Yes. The Pregnancy Due Date Calculator is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.

Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.