Pregnancy Due Date Calculator

Estimate your due date and current pregnancy week from your last menstrual period.

First day of last period

Cycle length (optional) days

Fill in the fields above and press Calculate or hit Enter ↵

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Pregnancy due date and week tracking basics

Last updated: March 30, 2026

A due date calculator estimates delivery date from the first day of the last menstrual period, typically using a 40-week baseline with cycle-length adjustment.

It also provides current pregnancy week and trimester, helping users understand timing milestones before their next prenatal appointment.

This is an estimate for planning and should be confirmed with prenatal care professionals and clinical dating methods.

Frequently asked questions

How is due date calculated?

Standard due date uses 280 days (40 weeks) from the first day of the last menstrual period, with cycle-length adjustment if needed.

Can cycle length change the due date?

Yes. Longer or shorter cycles can shift ovulation timing, so this calculator adjusts from the 28-day baseline.

Should I rely only on this estimate?

No. Use this as an early estimate and confirm dating with your prenatal healthcare provider.