Health & Fitness
Fetal Weight Percentile Calculator
Estimate fetal weight percentile by gestational age.
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What percentile is normal?
10th to 90th percentile is typically considered normal. Below 10th may indicate growth restriction.
How accurate are ultrasound weights?
Estimates can be off by 10-15%, especially in late pregnancy.
What if baby is small/large?
Your doctor will monitor closely. Many factors affect size, and one measurement isn't definitive.
Related tools
About this tool
Inputs
- Gestational Age (weeks)
- Estimated Fetal Weight
Results
- Percentile
- Size Category
- Normal Range
- Small for Gestational Age
- Appropriate for Gestational Age
- Large for Gestational Age
Before making a decision based on estimates, run the numbers through this Fetal Weight Percentile Calculator. A few seconds of input can save hours of uncertainty. Reference ranges published by organizations like WHO and NIH apply to general adult populations and may not suit everyone. Basal metabolic rate estimates use equations like Harris-Benedict or Mifflin-St Jeor, which factor in age, sex, height, and weight. Start by filling in gestational age (weeks) and estimated fetal weight. Based on these values, the tool computes percentile, size category, normal range and other key metrics.
From students to professionals, anyone who needs to estimate fetal weight percentile by gestational age benefits from getting an instant, verifiable answer. Your doctor will monitor closely. Many factors affect size, and one measurement isn't definitive. Consider multiple indicators together rather than focusing on a single number. Tracking health indicators over time reveals trends that one-off measurements miss. Use the result as a starting point for deeper analysis. Pair it with other tools for a more complete picture.