Newborn weight loss calculator
Most newborns lose some weight in the first days and then regain it; this shows the exact percentage so you know when to seek a check.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter birth weight and current weight.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Loss % = (birth weight - current weight) ÷ birth weight × 100. Under 7%: usual range. 7% to under 10%: feeding review. 10% or more: prompt medical review.
Example
Inputs: Birth weight = 3,500 g, Current weight = 3,290 g. Result: Loss from birth weight: 6%; Weight lost: 210 g; Assessment: Under 7%: within the usual early range.
Limits and caveats
- Compare weights from the same scale with similar or no clothing; small differences change the result.
- It does not replace a check-up, especially with few wet diapers, sleepiness or jaundice.
Questions about this tool
How much weight do newborns usually lose?
Many lose about 5% to 7% in the first three or four days, then start gaining.
When do babies regain birth weight?
Most are back to birth weight within 10 to 14 days.
Why the 7% mark?
The American Academy of Pediatrics notes that a loss above 7% may point to feeding problems and needs a closer look.