FreeNo signup
Pregnancy Week Calculator
Count completed gestational weeks and days on a reference date from the first day of the last menstrual period.
- Completed weeks and days
- 13 weeks 2 days
- Total gestational days
- 93
How the calculation works
Gestational days = reference date − first day of the last period; weeks = whole days/7.
Inputs
- First day of last period
- Reference date
Calculation details
Dates are approximate and do not confirm pregnancy. A clinician establishes gestational dating using history and ultrasound; IVF requires separate dating.
Gestational age starts at the last period, usually about two weeks before conception. This calculation assumes a 28-day cycle.
Related calculators
- Age Difference Calculatorage difference calculatorOpen →
- Conception Date Calculatorconception date calculatorOpen →
- Menstrual Cycle Calculatorperiod calculatorOpen →
- Ovulation Calculatorovulation calculatorOpen →
- Pregnancy Due Date Calculatorpregnancy due date calculatorOpen →
- Pregnancy Weight Gain Calculatorpregnancy weight gain calculatorOpen →
Other sections
Updated: 2026-10-02