New Born Weight Loss Calculator

The New Born Weight Loss Calculator estimates weight loss percentage based on birth weight, current weight, and age in days. This tool helps new parents and healthcare providers monitor infant hydration and health early on. Whether you are tracking feeding progress, checking for dehydration, or monitoring recovery to birth weight, this calculator provides clear guidance to keep your baby safe.

Enter your baby's birth weight in grams (g)
Enter your baby's current weight in grams (g)
Enter your baby's age in days (0-30 days)
Approximate percentile of baby's birth weight (if known)

How Weight Loss Percentage Is Calculated

Weight Loss Percentage represents the portion of body weight a newborn has lost since delivery. We use a standard percentage formula to determine this figure accurately.

((Birth Weight - Current Weight) / Birth Weight) * 100

Where:

  • Birth Weight is the baby's weight at delivery.
  • Current Weight is the weight measured today.
  1. First, subtract the current weight from the birth weight to find the total loss.
  2. Then, divide that number by the birth weight to find the ratio.
  3. Finally, multiply by 100 to convert the ratio into a percentage.

This method is widely used by pediatricians because it accounts for the baby's specific size, offering a clear view of hydration and feeding effectiveness in the first weeks of life.

What Your Weight Loss Percentage Means

This number shows if your baby is maintaining healthy fluid levels or losing too much weight. It helps you decide if current feeding routines are working or if changes are needed to support growth.

Normal Range (0% to 10%)
A loss in this range is typical for the first few days after birth. It suggests your baby is adjusting well to feeding. You should continue routine feeding and monitor daily wet diapers to ensure steady progress.

Slightly High (10% to 12%)
This result indicates a need for closer attention. You may need to feed more often or wake the baby for feeds. Consulting a lactation specialist to check latch and milk transfer is often helpful in this range.

High (Greater than 12%)
Loss above 12% is a serious sign of dehydration and requires immediate action. You should contact your pediatrician right away to assess the baby's health and create a feeding plan.

Important

Remember that age and feeding method significantly impact these ranges. A 10% loss might be acceptable on day three but not on day ten.

This tool is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Pro Tip

To track trends accurately, try to weigh your baby at the same time of day, ideally before a feeding.