Conception Calculator

Estimate when conception occurred based on your due date.

Conception Calculator

App • Fertility & Cycle Tracking

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How to calculate conception date

Estimate when you conceived based on your expected due date or last menstrual period.

Due date

Conception usually happens about 38 weeks before the due date.

Calculation

We subtract 266 days from your due date to find the probable conception window.

Accuracy

This is an estimate, as ultrasound measurements provide the most accurate dating.

Common Questions

Why use due date instead of last period?

If your cycles are irregular, an ultrasound-based due date is more accurate for finding conception.

Can I know the exact day?

Sperm can live up to 5 days, so conception is usually a window rather than a single day.

Steps For

PregnancyMothers to beUltrasound dating

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