Due Date Calculator (LMP / Naegele)
Estimated due date from your last period with cycle-length adjustment — plus what 'due date' statistically means.
Naegele's 280-day rule assumes ovulation on day 14 — the cycle adjustment shifts it for longer or shorter cycles. Only ~4% of babies arrive on their EDD; 90% arrive within two weeks either side. A first-trimester ultrasound, when it disagrees by more than a few days, overrides the LMP date (ACOG).
Formula
For general information only. Pregnancy and infant care decisions must be guided by your treating clinician or midwife — always defer to their assessment.
Estimated due date from your last period with cycle-length adjustment — plus what 'due date' statistically means. The Due Date Calculator (LMP / Naegele) is a free, private due date calculator tool — every result computes instantly in your browser with no sign-up and no data upload.
About Due Date Calculator (LMP / Naegele)
Naegele's 280-day rule assumes ovulation on day 14 — the cycle adjustment shifts it for longer or shorter cycles. It applies EDD = LMP + 280 days + (cycle length − 28). Use the Due Date Calculator (LMP / Naegele) to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Due Date Calculator (LMP / Naegele)
- 1Enter your details in the Due Date Calculator (LMP / Naegele) input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Due Date Calculator (LMP / Naegele)?
- ✓Instant due date calculator result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (ACOG Committee Opinion 700 — methods for estimating the due date)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Due Date Calculator (LMP / Naegele) work?+
Naegele's 280-day rule assumes ovulation on day 14 — the cycle adjustment shifts it for longer or shorter cycles. The calculation uses the formula: EDD = LMP + 280 days + (cycle length − 28). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Due Date Calculator (LMP / Naegele) accurate, and what is it based on?+
The method is traceable to authoritative sources: ACOG Committee Opinion 700 — methods for estimating the due date. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Due Date Calculator (LMP / Naegele) free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is informational only. Always defer to your treating clinician or midwife for pregnancy and infant care decisions.
What can I use the Due Date Calculator (LMP / Naegele) for?+
It's commonly used for due date calculator, edd calculator, pregnancy due date. Estimated due date from your last period with cycle-length adjustment — plus what 'due date' statistically means.
Related Health tools
Adult BMI Calculator (WHO)
Body-mass index for adults with the WHO reference bands shown neutrally, plus the substituted formula step by step.
● LiveBMI Calculator (lb & inches)
US-style BMI from pounds and inches using the ×703 conversion, with CDC adult reference ranges.
● LiveBMI Calculator for Women
BMI with reference context written for women — what the index can and cannot say about female body composition.
● Live