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HEALTH

Pregnancy Calculator

Estimate pregnancy milestones from a period, conception, due date, ultrasound, or IVF transfer.

Choose what you knowUse a menstrual, conception, due-date, ultrasound, or IVF date.
5 options
ESTIMATED DUE DATEOctober 8, 2026

Based on the last menstrual period. Educational estimate only; not medical advice.

Estimated due date
October 8, 2026
Estimated conception date
January 15, 2026
Estimated gestational start
January 1, 2026
Estimated second trimester
April 9, 2026
Estimated third trimester
July 16, 2026
Estimate based on the values shown
MethodNaegele-style 280-day dating with cycle-length adjustment, plus conception, ultrasound, and IVF transfer methods.

Before you use the result

Educational estimate only; it cannot diagnose a condition or replace advice from a qualified health professional.

Sources

EDITORIAL NOTES

Using the Pregnancy Calculator responsibly

Page-specific guidance based on this calculator’s implemented method, inputs, and known limits.

What this result is useful for

Pregnancy dating estimates a due date and related milestones from the information selected: last menstrual period, conception date, ultrasound dating, IVF transfer, or an existing due date. These methods can produce different estimates because they use different evidence.

Assumptions and limits

Last-period dating assumes a typical relationship between cycle timing and ovulation, with the entered cycle adjustment. Conception may be uncertain, and clinical ultrasound interpretation depends on gestational age and measurement. The result is not a confirmation of pregnancy or fetal wellbeing.

How to check the result

Check every calendar date and the direction of any cycle adjustment. Prenatal records should use the due date established by the treating clinician, especially after ultrasound or assisted reproduction. Contact a qualified professional for symptoms, medication questions, or urgent concerns.

Content review: August 30, 2026
CALCULATOR GUIDE

How to use the Pregnancy Calculator

Estimate pregnancy milestones from a period, conception, due date, ultrasound, or IVF transfer. It includes Last menstrual period, Conception date, Due date, Ultrasound, IVF transfer workflows, so choose the one that matches the values you actually know. Use it to understand an educational estimate and the inputs behind it, not as a diagnosis or treatment decision.

Step by step

  1. For the Pregnancy example, select Last menstrual period and enter first day of your last period, average length of your cycles. Keep each value in the unit displayed beside its field.
  2. Review the selected Pregnancy workflow and inputs, then read estimated due date in the result panel.
  3. Change one Pregnancy assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.

How the calculation works

Naegele-style 280-day dating with cycle-length adjustment, plus conception, ultrasound, and IVF transfer methods.

Worked example

To reproduce the Pregnancy worked example, reset the calculator. Select the Last menstrual period workflow. Use first day of your last period 2026-01-01; average length of your cycles 28 days. The result is estimated due date of October 8, 2026. Based on the last menstrual period. Review the displayed units before comparing the result.

Understanding the result

The Pregnancy reports estimated due date. Use it to understand an educational estimate and the inputs behind it, not as a diagnosis or treatment decision. Educational estimate only; it cannot diagnose a condition or replace advice from a qualified health professional.

How to check the answer

Check the Pregnancy estimate by confirming the units and supported ranges for first day of your last period, average length of your cycles. Compare estimated due date with another published method or direct measurement when available, and ask a clinician before using it for a health decision.

Common questions

What does the Pregnancy calculate?

Estimate pregnancy milestones from a period, conception, due date, ultrasound, or IVF transfer.

Which inputs does the Pregnancy example use?

The worked example uses first day of your last period, average length of your cycles in the Last menstrual period workflow. Other workflows can show different fields. Keep the chosen workflow and units with the result when comparing calculations.

Is the Pregnancy result exact?

Educational estimate only; it cannot diagnose a condition or replace advice from a qualified health professional. Recheck first day of your last period, average length of your cycles and use estimated due date only for a decision where that level of precision is appropriate.

Formula tests, limits, and sources reviewed September 1, 2026. Guide examples updated October 12, 2026.
INTERPRET THE RESULTRead the health guideCheck assumptions, limitations and comparison methods →
KEEP GOING

Useful next steps

Pregnancy Weight GainEstimate pregnancy weight gain from your current pregnancy stage, pregnant with twins, your weight before pregnancy with the Pregnancy Weight Gain Calculator.Pregnancy ConceptionWork backward to an estimated conception date from a due date, period, ultrasound, or IVF transfer.Due DateEstimate a due date from a period, conception date, ultrasound, IVF transfer, or existing due date.