Due Date Calculator

Estimate an expected due date from LMP, conception, or IVF transfer and review milestone dates across the pregnancy timeline.

Last updated: March 13, 2026

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Pregnancy and fertility notice

Due-date and ovulation outputs are estimates based on cycle or transfer-date assumptions, not guarantees of conception timing or delivery timing.

Use them for planning conversations only, and confirm important decisions with a licensed clinician or fertility specialist.

Interactive tool

The live form, validation, and result state for Due Date Calculator load after the page scripts run. The content below summarizes how the tool works and links to related pages in the catalog.

Estimate due date and pregnancy milestones using last menstrual period, conception date, or IVF transfer date with embryo-age support.

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How to use Due Date Calculator

1
Enter your inputs into the Due Date Calculator form.
2
Adjust optional settings so the scenario matches your real-world case.
3
Review the result, then tweak one variable at a time to compare outcomes.
4
Keep your best scenario as a baseline for future decisions.

Health and pregnancy tools are informational only. For diagnosis or treatment, rely on licensed clinical guidance.

Best use cases

Compare realistic due date calculator scenarios without switching between spreadsheets or separate references.

Change one assumption at a time to see how the result moves.

Use the interactive output as a quick planning baseline before deeper review.

Worked example

Cycle-based planning example

If the last menstrual period started on January 10, 2026, the calculator can estimate a due date and key trimester checkpoints from that baseline.

Use LMP mode when you know the start date of the last period.
Compare that estimate with conception or IVF mode if you have more precise information.
Treat milestone dates as planning references until confirmed by a clinician.

This tool is most useful for orientation and planning questions, not for confirming exact clinical dating.

Methodology

LMP mode estimates due date by adding a standard gestational window to the last menstrual period.
Conception mode starts from the known conception date and maps milestone dates forward from that point.
IVF mode adjusts from transfer date plus embryo age before calculating estimated gestational timing.

Tips for better results

Validate all required inputs before trusting the result.
Test at least one conservative scenario before acting on the output.
Recalculate when your assumptions, costs, or constraints change.

FAQ

Which method is most accurate?

The best method depends on what information you know. IVF transfer dates and known conception dates are usually more precise than a cycle-based estimate from LMP alone.

Can this calculator handle IVF dates?

Yes. You can choose IVF transfer date and specify whether the embryo was transferred on day 3 or day 5.

Does the due date predict the exact delivery day?

No. Due dates are estimates. Delivery can happen before or after the estimated date.

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Key assumptions

Cycle-based estimates assume standard gestational timing and a correctly remembered start date.
IVF mode assumes the transfer date and embryo age entered are accurate.

Important limitations

This calculator does not replace ultrasound dating, prenatal care, or clinician guidance.
Irregular cycles, multiple gestation, and pregnancy-specific complications can change milestone timing.