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

Jun 27, 2027

Gestational Age0 weeks, 0 days

Estimated ConceptionOct 4, 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

Sep 20, 2026 – Dec 19, 2026

2nd TrimesterWeeks 13–26

Dec 20, 2026 – Mar 27, 2027

3rd TrimesterWeeks 27–40

Mar 28, 2027 – Jun 27, 2027

Key Milestones

First Heartbeat Detectable~Week 6

Nov 1, 2026

End of First Trimester~Week 12

Dec 13, 2026

First Fetal Movement~Week 18

Jan 24, 2027

Viability Milestone~Week 24

Mar 7, 2027

Third Trimester Begins~Week 27

Mar 28, 2027

Full Term~Week 37

Jun 6, 2027

Learn more

How do cycle trackers predict ovulation, and why do cycle lengths vary?

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DueDateCalculator