Pregnancy Trimester Calculator

Enter your due date to find out which week and trimester you're in, and see key milestone dates for your pregnancy journey.

What are Pregnancy Trimesters?

A full-term pregnancy typically lasts 40 weeks and is divided into three distinct stages called trimesters. Each is about three months long and comes with its own specific fetal development milestones and changes for the expectant mother.

This is a period of rapid development. Key organs form, and the mother's body undergoes significant hormonal changes, which can lead to common symptoms like morning sickness and fatigue.

Often called the "honeymoon" phase, many women feel more energetic as early symptoms subside. The baby grows larger, a bump becomes visible, and you may feel the first flutters of movement.

The baby continues to gain weight and mature, preparing for birth. This trimester involves preparing for labor and may bring physical discomforts due to the baby's size.

Track Your Pregnancy

Maintained by Live Fitness Check. Last updated: August 9, 2026. How we test our calculators .

About This Calculator

Pregnancy Trimester Calculator estimates the current pregnancy trimester from pregnancy dating information. It is designed to give a quick, understandable estimate from pregnancy dating information entered on the calculator so the result can be used as a starting point for learning, tracking or a more informed discussion.

Methodology

Inputs used: Pregnancy dating information entered on the calculator.
Calculation approach: The calculator converts the pregnancy date into gestational age and assigns the corresponding trimester according to its configured week ranges.
Interpretation: Results are presented as an estimate and should be read together with the limitations described below.

Sources

ACOG — Methods for Estimating the Due Date: https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/05/methods-for-estimating-the-due-date

Disclaimer

This calculator is for general informational and educational use. Clinical pregnancy dating may be revised using ultrasound and obstetric assessment. Do not use the result as a diagnosis, emergency assessment, or a replacement for advice from an appropriately qualified health professional when medical decisions are involved.

Frequently Asked Questions

What does the Pregnancy Trimester Calculator estimate?

Estimates the current pregnancy trimester from pregnancy dating information.

How is this result calculated?

The calculator converts the pregnancy date into gestational age and assigns the corresponding trimester according to its configured week ranges. The calculation uses pregnancy dating information entered on the calculator.

How should I use the result?

Clinical pregnancy dating may be revised using ultrasound and obstetric assessment. Use the number as an estimate and consider professional advice when the result may affect health, treatment, pregnancy, nutrition, exercise safety or another important decision.