Calculadora de Semanas de Gravidez Online Grátis
Due date via Naegele's Rule with milestone tracker
This calculator estimates your baby's due date using Naegele's Rule — the standard obstetric formula that adds 280 days (40 weeks) to the first day of your last menstrual period. Alongside the estimated due date, it shows key pregnancy milestones by trimester so you know what to expect at each stage.
Frequently Asked Questions
Sobre Esta Calculadora
Naegele's Rule has been the standard method for calculating due dates since the 1800s, named after German obstetrician Franz Karl Naegele. The rule assumes a 28-day cycle with ovulation on day 14 — which is an average, not a universal reality. Women with longer or shorter cycles may have due dates that differ slightly from this calculation.
The 40-week timeline is counted from the LMP, not from conception. Since ovulation typically occurs about 14 days into the cycle, fertilization usually happens around the start of week 3. This means a fetus is actually about 38 weeks old at the time of a "40-week" due date.
Most healthcare providers confirm the due date with an early ultrasound (before 14 weeks), which can measure fetal crown-to-rump length to give a more accurate gestational age estimate. The LMP-based calculation and ultrasound measurement together give the most reliable due date.
Esta calculadora estima a data prevista do parto usando a Regra de Naegele e a sua última menstruação.
Fórmula
EDD = LMP + 280 days (40 weeks) Naegele's Rule: LMP + 1 year - 3 months + 7 days
Exemplo Resolvido
Calculating due date from last menstrual period
Entradas:
- Last Menstrual Period (LMP): March 10, 2025
- Average cycle length: 28 days
Passo a Passo:
- Apply Naegele's Rule: LMP + 280 days
- March 10, 2025 + 280 days = December 15, 2025
- Alternative method: LMP + 1 year − 3 months + 7 days
- = March 10, 2026 − 3 months + 7 days = December 17, 2025 (minor rounding difference)
- First trimester ends: ~June 16, 2025 (week 12)
- Second trimester ends: ~September 22, 2025 (week 27)
- Full term window: November 24 – December 29, 2025 (37–42 weeks)
Dicas
- Only ~5% of babies arrive on their exact due date. A 'normal' full-term delivery is 37-42 weeks.