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Pregnancy Trimester Calculator

Current trimester and weeks left from LMP.

Determine the current trimester, gestational age in weeks, and weeks remaining until the estimated due date from the first day of your last period.

Priya Venkatesan By Priya Venkatesan
Reviewed by Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Trimester 1: weeks 1–13. Trimester 2: weeks 14–27. Trimester 3: weeks 28–40.

In depth

Determine the current trimester, gestational age in weeks, and weeks remaining until the estimated due date from the first day of your last period.