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.

Sante

Instantané, privé et gratuit

Calculateur de Date d'Accouchement.

4 août 2026

Calculez votre date d'accouchement selon vos dernieres regles

Cette calculatrice n'est pas encore entièrement traduite ; une partie du texte s'affiche en anglais.

Calcul sur l'appareilSans inscription

Saisissez vos valeurs

Les résultats se mettent à jour pendant la saisie.

02 / RÉPONSE

Dernières Règles

Entrez le premier jour de vos dernières règles. L'estimation suppose un cycle régulier de 28 jours et une grossesse de 280 jours.

Last Menstrual Period Date

Note: Based on standard 40-week gestation

Due Date

August 18, 2027

280 Days To Go

Progress

0w 0d

Trimester

1st

Progress0%

Conception Date: ~11/25/2026

Elapsed: 0 Weeks

Milestone: Entering Second Trimester

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Cite this calculator

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

Updated 4 août 2026

Cite as: Mathify. (2026). Calculateur de Date d'Accouchement. https://mathify.one/fr/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