Due
Date
Calculator

Calculate your estimated due date, gestational age, trimester timeline, and pregnancy milestones from your last menstrual period.

Input

First Day of Last Period

Average Cycle Length (days)

Estimated Due Date

Your baby is due

Dec 25, 2026

Gestational Age0 weeks, 0 days

Estimated ConceptionApr 3, 2026

Current Trimester1st Trimester

How It Works

This calculator uses Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP) to estimate your due date.

If your cycle length differs from 28 days, the estimate adjusts accordingly. A longer cycle shifts the due date later; a shorter cycle shifts it earlier.

This calculator provides estimates only. Actual due dates may vary. Consult your healthcare provider for personalized guidance.

Trimester Breakdown

1st TrimesterWeeks 1–12

Mar 20, 2026 – Jun 18, 2026

2nd TrimesterWeeks 13–26

Jun 19, 2026 – Sep 24, 2026

3rd TrimesterWeeks 27–40

Sep 25, 2026 – Dec 25, 2026

Key Milestones

First Heartbeat Detectable~Week 6

May 1, 2026

End of First Trimester~Week 12

Jun 12, 2026

First Fetal Movement~Week 18

Jul 24, 2026

Viability Milestone~Week 24

Sep 4, 2026

Third Trimester Begins~Week 27

Sep 25, 2026

Full Term~Week 37

Dec 4, 2026

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DueDateCalculator