Health calculators

Pregnancy Due Date Calculator

Estimate a due date from the first day of the last menstrual period using Naegele’s rule (LMP + 280 days).

Estimates only — not medical advice. Formulas are simplified screening tools. Talk to a qualified clinician for health decisions.

Estimated due date

2026-10-22

How to use

  1. Enter the first day of your last menstrual period.
  2. Read the estimated due date.
  3. Confirm dating with a clinician — ultrasound dating may differ.

Features

  • Naegele’s rule (280 days)
  • Simple date input
  • Private browser calculation

Privacy & how it works

This calculator runs entirely in your browser with JavaScript. Your inputs are not uploaded to ToolsWeb servers for this tool. Privacy Policy · Disclaimer.

FAQ

Is this a medical due date?expand_more

No. It is a common estimate. Clinical dating can change the date.

Is this calculator free?expand_more

Yes. No signup required.

Are my numbers uploaded?expand_more

No. Calculations run in your browser. Inputs are not sent to ToolsWeb servers for this tool.

Is this professional advice?expand_more

No. Results are estimates for general information. See our Disclaimer for health, finance, and related tools.

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