How is my due date calculated?

The calculator uses the first day of your last menstrual period (LMP) and adds 280 days (40 weeks) to estimate your due date. This is the standard Naegele's rule, assuming a regular 28-day cycle.

Can I find out my conception date?

Yes, the calculator estimates your conception date by subtracting 266 days (38 weeks) from your due date, which is the average time from conception to birth. This is an estimate, as conception can vary by a few days.

What if my cycle is irregular?

The calculator assumes a regular 28-day cycle. If your cycle is longer or shorter, your due date may differ. For the most accurate estimate, consult your healthcare provider, who may use ultrasound measurements.

Salud

Instantáneo, privado y gratis

Calculadora de Fecha de Parto.

4 ago 2026

Calcula tu fecha estimada de parto basada en tu ultimo periodo

Esta calculadora aún no está totalmente traducida; parte del texto se muestra en inglés.

Cálculo en el dispositivoSin registro

Introduce tus valores

Los resultados se actualizan al escribir.

02 / RESPUESTA

Última Menstruación

Ingresa el primer día de tu último periodo. La estimación asume un ciclo regular de 28 días y un embarazo de 280 días.

First Day of Last Period

Note: This is an estimate, not a prediction. Only a small share of births happen on the estimated due date, and a healthcare provider can give a more accurate date from an ultrasound.

Estimated Due Date

August 18, 2027

280 days to go

Current Progress

0w 0d

Trimester

1st

Progress0%

Estimated Conception Date: ~11/25/2026

Time Elapsed: 0 weeks

Next Milestone: Entering the second trimester

Calculadoras relacionadas

Ovulation CalculatorTrack your fertile window and next period Countdown TimerLive countdown to any date — days, hours, minutes and seconds, updating every second.Date CalculatorAdd or subtract days, weeks, months from dates Date DifferenceCalculate time between two dates Bedtime CalculatorCalculate ideal bedtimes from your target wake-up time Dog Age CalculatorConvert dog years to human years using modern science based on breed size

Cite this calculator

Canonical URL: https://mathify.one/es/health/due-date

Updated 4 ago 2026

Cite as: Mathify. (2026). Calculadora de Fecha de Parto. https://mathify.one/es/health/due-date

Use Cases

Plan for your baby's arrival

Know your estimated due date to plan maternity leave, prepare the nursery, and schedule prenatal appointments.

Example: Enter your LMP to see your due date and current pregnancy week.

Track pregnancy progress

Monitor how far along you are and what to expect each week, helping you stay informed about your baby's development.

Example: At 20 weeks, you're halfway through your pregnancy.

Frequently Asked Questions

How is my due date calculated?: The calculator uses the first day of your last menstrual period (LMP) and adds 280 days (40 weeks) to estimate your due date. This is the standard Naegele's rule, assuming a regular 28-day cycle.
Can I find out my conception date?: Yes, the calculator estimates your conception date by subtracting 266 days (38 weeks) from your due date, which is the average time from conception to birth. This is an estimate, as conception can vary by a few days.
What if my cycle is irregular?: The calculator assumes a regular 28-day cycle. If your cycle is longer or shorter, your due date may differ. For the most accurate estimate, consult your healthcare provider, who may use ultrasound measurements.

Tips & Common Mistakes

Tips

Enter the first day of your last menstrual period accurately for the best estimate.
Remember that only about 5% of babies are born on their exact due date; it's normal to give birth a week or two before or after.
Use the conception date estimate to understand your pregnancy timeline, but rely on ultrasound for precise dating.
If your cycle is longer than 28 days, your due date may be later; consider discussing with your doctor.

Common Mistakes to Avoid

Using the date your period ended instead of the first day of your last period.
Assuming the due date is exact; it's an estimate and can change based on ultrasound findings.
Forgetting to account for irregular cycles, which can affect the accuracy of the calculation.

Last updated: August 13, 2026