Fetal growth calculator tool showing baby size by pregnancy week
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Fetal Growth Calculator - Free Pregnancy Tracker | Healthtus
Healthtus Health Tool

Fetal Growth Calculator (Pregnancy Tracker)

Track your baby's growth and development with our free Fetal Growth Calculator. Choose from LMP, Conception, Ultrasound, or IVF methods to calculate your estimated due date, gestational age, and current trimester. Get weekly fetal development insights and visualize your pregnancy timeline.

100% Free No Registration Instant Results Privacy First Pregnancy Tracking
Due date: --
Calculate Fetal Growth

Fetal Growth Calculator

Please select a calculation method.
Please select a valid date.
Please enter a cycle length between 21–45 days.
Please enter weeks between 6–40.
Please enter days between 0–6.
Please select the current date.

Your Fetal Growth Results

Your pregnancy summary will appear here.
Weeks Pregnant
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Conception Date
--
Due Date
--
Gestational Age
--
Trimester
--
LMP Date
--
Fetal Development
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--
Pregnancy Weeks
Conception
Due Date

What This Means

Complete the form and click "Calculate" to see personalized insights about your pregnancy and baby's development.

How to Use the Tool

1. Select method

LMP, Conception, Ultrasound, or IVF.

2. Enter date

Your chosen date + current date.

3. Get insights

Due date, gestational age & development.

How It's Calculated

Key Formulas

  • LMP Method: Due Date = LMP + 280 days
  • Conception: Due Date = Conception + 266 days
  • Ultrasound: LMP = US Date − (Weeks × 7 + Days)
  • IVF: LMP = Transfer − Embryo Age − 14 days

Method Details

  • Single Pregnancy: 280 days from LMP
  • Multiple Pregnancy: ~266 days from LMP
  • Gestational Age: Weeks since LMP
  • Trimester: 1st (1–13), 2nd (14–27), 3rd (28+)
Worked example: LMP = Jan 1 → Due Date = Oct 7 (280 days) → At current date (Apr 1), Gestational Age = 13 weeks → 2nd Trimester.

About Fetal Growth

What is Gestational Age?

Gestational age is the age of the pregnancy calculated from the first day of the last menstrual period (LMP). It is measured in weeks and days. A full-term pregnancy is typically 40 weeks (280 days) from LMP. Fetal growth milestones help track your baby's development throughout the pregnancy.

Key Milestones:

  • 4 Weeks: Neural tube formation begins
  • 8 Weeks: Major organs developing
  • 12 Weeks: Fingernails form
  • 20 Weeks: Vernix caseosa forms
  • 28 Weeks: Eyes open
  • 40 Weeks: Full term, average birth size

Limitations of This Tool

  • Provides estimates based on standard pregnancy dating — individual variations exist.
  • Does not account for cycle irregularities or ovulation timing variations.
  • Not a substitute for professional medical advice or ultrasound dating.
  • Due dates are estimates — only about 5% of babies arrive on their due date.

Trust & Privacy

Your data stays in your browser. All calculations happen locally. We never send your data to any server.

No registration or login required. Your privacy is 100% protected.

Uses standard pregnancy dating methods. Our tool follows established obstetric guidelines.

No cookies used for tracking. Your history is stored locally in your browser's localStorage.

Standard Methods
Data stays in your browser
No registration needed
Mobile-friendly
Updated frequently
Completely free

Real-World Examples

Example 1

LMP: Jan 1, Cycle: 28 days

Due Date: Oct 7

Example 2

Conception: Jan 14

Due Date: Oct 7

Example 3

Ultrasound: Jun 1 (12w), Current: Aug 1

Due Date: Dec 7

Frequently Asked Questions

This calculator provides estimates based on standard pregnancy dating methods. Accuracy depends on the method used and the regularity of your cycle. Ultrasound dating is generally considered the most accurate method for determining gestational age.
LMP calculates from the first day of your last period. Conception uses the estimated date of conception. Ultrasound uses a dating scan to determine gestational age. IVF uses the embryo transfer date. Each method is appropriate for different situations.
Multiple pregnancies (twins, etc.) typically have shorter gestations. The calculator adjusts the due date by using 266 days from LMP instead of 280 days, which reflects the tendency for multiple births to occur earlier.
The IVF method uses the date of embryo transfer. For a 3-day embryo, conception is 3 days before transfer. For a 5-day embryo, conception is 5 days before transfer. The calculator then determines LMP and due date accordingly.
A baby is considered full term between 39 weeks and 40 weeks + 6 days. Early term is 37–38 weeks, and late term is 41 weeks. Post-term is 42 weeks and beyond.
Your data is stored locally in your browser's localStorage. It is not sent to any server or stored by Healthtus. You can clear your history at any time.
Our team reviews and updates the tool regularly, with the latest review completed in July 2026.

References

  • American College of Obstetricians and Gynecologists. Methods for Estimating the Due Date. acog.org
  • World Health Organization. Pregnancy, childbirth, postpartum and newborn care. who.int
  • National Institutes of Health. Fetal Development. nichd.nih.gov

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Your History

No calculations yet.

Editorial & Medical Review

Reviewed by: Healthtus Editorial Team
Credentials: Evidence-based, ACOG standards
Last Updated: July 2026
Sources: ACOG, WHO, NIH
Editorial Policy: Read our policy

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