Calculadora de Ovulação
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
ovulação ≈ dia_1 + (ciclo − 14)
About this calculator
The Ovulation Calculator estimates your most fertile day by using the first day of your last menstrual period and your average cycle length. The formula is: ovulation day ≈ first day of last period + (cycle length − 14). This gives the approximate day when an egg is released and can be fertilized for up to 24 hours.
To use it, enter the date of your last period and your typical cycle duration (usually 21 to 35 days). The tool then shows the estimated ovulation day and the fertile window (about 5 days before ovulation). Keep in mind that this method assumes regular cycles and that ovulation occurs 14 days before your next period, which may vary.
Common uses include family planning, whether to conceive or as a supplementary method to avoid pregnancy. It also helps women understand their cycle and detect irregularities. However, it should not replace reliable contraception or medical advice.
Important precautions: irregular cycles, stress, illness, or medications can affect ovulation. The calculation is an estimate and not guaranteed. For better accuracy, combine with other fertility signs like cervical mucus or basal body temperature. Consult a gynecologist for personalized guidance.
Frequently asked questions
What if my cycle is irregular?
The calculator works best with regular cycles. If your cycle varies, results will be less accurate. Consider tracking other fertility signs or consulting a doctor.
Can this calculator be used as birth control?
It is not recommended as a sole method, as ovulation can vary. Use along with condoms or other methods for better protection.
How many days before ovulation am I fertile?
The fertile window starts about 5 days before ovulation and ends on ovulation day. Sperm can survive up to 5 days in the reproductive tract.
Can stress delay ovulation?
Yes, physical or emotional stress, illness, and routine changes can alter your cycle and delay ovulation, affecting the calculation's accuracy.
Does the calculator replace an ovulation test?
No. Ovulation tests measure LH hormone in urine and are more accurate. The calculator is an initial estimate.