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Pregnancy Week Calculator

Calculate the current gestational age and number of days based on the last menstrual period, embryo transfer date, or expected due date confirmed by a doctor.

Formula DisclosureFront-end only computation · Input not savedFor estimation reference only

Enter Information

Calculation result

Purpose

Estimate the current gestational age based on the last menstrual period, embryo transfer date, or confirmed due date.

Three Modes and Formulas

Natural conception: D = Current date − First day of last menstrual period.

IVF: D = Current Date − Transfer Date + 14 + Embryo Age in Days.

Given the estimated due date: D = 280 − (estimated due date − current date).

Gestational weeks = ⌊D ÷ 7⌋, remaining gestational days = D mod 7.

Output

Current gestational week, gestational days, trimester, and estimated due date.

Applicable Limitations

Do not mix the three modes. When a doctor has reconfirmed the gestational age based on an ultrasound, the information provided by the medical institution shall prevail.

Reference Sources

ACOG:Estimated Due Date Calculation Methods; NHS:Due date calculator

The estimates provided by this tool are for general reference only and cannot replace professional evaluation, diagnosis, or formal quotes from healthcare institutions. Please confirm gestational age, due date, and medication and surgery schedules with your doctor. All calculations are completed locally in your browser, and we do not store the health information you enter.