Baby Weight Estimator Calculator

How to Use This Calculator

To estimate your baby's weight, follow these steps:

1. Enter your baby's gestational age in weeks
2. Select your baby's sex (optional)
3. Click "Calculate" to get the estimated weight
4. Review the result and interpretation

The calculator uses standard growth charts and statistical averages to provide an estimate. Remember that actual baby weights can vary significantly from these estimates.

Formula Used

The baby weight estimator uses a combination of gestational age and birth weight percentiles to calculate an estimated weight. The formula is:

Where:

• Base Weight is the average birth weight at 40 weeks
• Gestational Age is the number of weeks since conception
• Growth Rate is the average daily weight gain

For preterm babies, the calculator uses adjusted growth curves based on medical research.

Interpreting Results

The estimated weight provides a general idea of your baby's size. Keep in mind:

• Actual birth weight may vary by several pounds
• Preterm babies may have different growth patterns
• Sex differences can affect birth weight

Use this estimate to prepare for your baby's arrival, but always consult with your healthcare provider for personalized advice.

Worked Examples

Example 1: Full-term Baby

For a baby at 40 weeks gestation:

• Base Weight: 3,500 grams
• Growth Rate: 0 grams (since at full term)
• Estimated Weight: 3,500 grams (7.7 pounds)

Example 2: Preterm Baby

For a baby at 32 weeks gestation:

• Base Weight: 1,500 grams
• Growth Rate: 25 grams per week
• Estimated Weight: 1,500 + (32-40) × 25 = 1,500 - 200 = 1,300 grams (2.9 pounds)