Pregnancy Due Date Calculator

Estimate your pregnancy due date, current week and trimester from the first day of your last menstrual period.

Pregnancy Due Date

Estimate due date and progress from the first day of the last menstrual period (Naegele's rule, +280 days).

First day of last period:

About the Pregnancy Due Date Calculator

Based on Naegele's rule (LMP + 280 days), this calculator estimates your due date, how far along you are in weeks and days, your current trimester, and how many days remain. It also estimates conception date.

Note: This is an estimate only. Always consult a medical professional for accurate pregnancy advice and care.

How it works

The calculator uses Naegele's rule: estimated due date = first day of last menstrual period + 280 days. Current pregnancy week comes from days elapsed since LMP, divided into weeks. Trimester boundaries: 1st = weeks 1–12, 2nd = 13–26, 3rd = 27 onward. Estimated conception is LMP + 14 days (assumes a 28-day cycle and ovulation on day 14).

Examples

LMP: Feb 1, 2026Due Nov 8, 2026 · Conception ~Feb 15, 2026
LMP: today0 weeks 0 days · Trimester 1

Frequently asked questions

How accurate is Naegele's rule?

It's a population estimate. About 4% of births occur on the exact predicted date; most fall within a two-week window. Cycle length, ovulation timing and fetal development all vary.

What if my cycle isn't 28 days?

For shorter or longer cycles, the conception estimate (LMP + 14 days) drifts. The 280-day due date is still the standard medical estimate regardless.

Should I use this for medical decisions?

No. Always consult your healthcare provider. This calculator is informational only.