Calculadora de Semanas de Gestação
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
IG = dias ÷ 7 + resto
About this calculator
The Pregnancy Weeks Calculator converts the Last Menstrual Period (LMP) into weeks and days of gestational age. The calculation is done in two steps: first, count the number of days between the LMP and the current date; then, divide that total by 7. The quotient represents the full weeks, and the remainder the extra days. For example, 180 days result in 25 weeks and 5 days. This tool helps pregnant women track fetal development, plan exams, and understand which trimester they are in.
Usage is simple: enter the LMP and the calculator does the rest. The result is displayed in weeks and days, the standard format used by obstetricians. The tool considers months with 30 or 31 days but does not adjust for leap years, as the difference is minimal for gestational age. Keep in mind that the LMP is a reference; the exact conception date may vary, especially in irregular cycles. Therefore, the result is an estimate, not a diagnosis.
Common use cases include: confirming the estimated due date (EDD) calculated by the doctor, checking weekly fetal progress, planning maternity leave, and comparing baby growth with percentile charts. The calculator is especially useful for women with regular 28-day cycles. For irregular cycles, ultrasound dating is more accurate. If in doubt, consult an obstetrician.
Frequently asked questions
How do I calculate gestational age if I don't remember my LMP?
If you don't remember your LMP, an early ultrasound is recommended, as it estimates gestational age based on fetal size. The calculator requires the LMP to work.
Does the calculator work for irregular menstrual cycles?
For irregular cycles, the result may be less accurate. Ultrasound is more reliable in this case. The calculator assumes a standard 28-day cycle.
What is the difference between gestational age and fetal age?
Gestational age is counted from the LMP (about 2 weeks before conception). Fetal age is counted from conception. The calculator shows gestational age.
Can I use the calculator to find the estimated due date?
Yes, but remember that the EDD is an estimate. The calculator can give an idea, but your doctor determines the date based on ultrasound and other factors.
What does the result in weeks and days mean?
The result shows how many full weeks of pregnancy you have and how many extra days have passed. For example, 25 weeks and 5 days means you are in the 26th week of pregnancy.