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Health and Fitness

Pregnancy and Due Date Calculator

Estimate a pregnancy due date from the last menstrual period or a known conception date using standard calendar rules.

Quick answer

Local calendar-date calculation using primary clinical guidance. Enter or select a known last-menstrual-period date; an estimated due date 280 days later is shown with clinical-dating caveats.

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  • No sign-up
  • Inputs stay in this browser
  • Clear limits and methodology
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Overview

What this tool does

Pregnancy and Due Date Calculator: Estimate a pregnancy due date from the last menstrual period or a known conception date using standard calendar rules. Explicit workflow boundaries Visible limitations and recovery Release-gated evidence

  1. Prepare a known last-menstrual-period date.
  2. Local calendar-date calculation using primary clinical guidance.
  3. Confirm that an estimated due date 280 days later is shown with clinical-dating caveats, then review the stated limits before copying or downloading anything.

Method

How this tool works

Local calendar-date calculation using primary clinical guidance. The calculation or transformation is deterministic for the same supported input, and the worked example below shows the intended scope.

Example

Pregnancy and Due Date Calculator worked example

Input: a known last-menstrual-period date.

Expected output: an estimated due date 280 days later is shown with clinical-dating caveats.

Limits

Assumptions and limits

  • Inputs and files stay in this browser and are excluded from analytics.
  • The worked example assumes a known last-menstrual-period date.
  • Units, dates, rates, selections and source-file quality are taken exactly as entered unless the workspace labels a default.
  • Pregnancy and Due Date Calculator is an educational estimate and does not diagnose, confirm or treat a health condition.
  • Use a qualified healthcare professional for symptoms, uncertainty, contraception, pregnancy dating or individual advice.

Privacy

Local processing

Values and files are processed locally in this browser unless the workspace explicitly identifies an optional network feature. Great Future does not intentionally collect tool inputs.

Sources

Method references and scope

Internal review owner: Great Future Health Methods Review.

  • Methods for Estimating the Due Date — American College of Obstetricians and Gynecologists. Reviewed 2026-08-29. Clinical guidance for establishing gestational age and an estimated due date.
  • Due date calculator guidance — NHS. Reviewed 2026-08-29. Patient-facing context for last-menstrual-period dating and cycle-length adjustment.

Questions

Frequently asked questions

What input should I prepare for Pregnancy and Due Date Calculator?

Prepare a known last-menstrual-period date. Keep the original values or file available so you can compare the result.

What should I verify after using Pregnancy and Due Date Calculator?

Verify that an estimated due date 280 days later is shown with clinical-dating caveats. Pregnancy and Due Date Calculator is an educational estimate and does not diagnose, confirm or treat a health condition.

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