Infant Growth Calculators – Metric

Many moms wonder if their baby is growing as expected. It may be helpful to use this calculator, together with the information in Average Weight Gain for Breastfed Babies, when analyzing your baby’s growth.

Directions: Fill in at least two rows (white columns only), then click on “calculate” to see the results.[Click here for English units (pounds, ounces, inches)]

Weight Gain Calculator
  Age     Weight  
  in weeks*     grams     grams gained per week  

* see the Age in Weeks Calculator

Age in weeks
Birth Date     [mm/dd/yyyy]
Current Date  (or any date)
Age in weeks      

  Average Growth for Breastfed Babies*
Baby’s Age


Avg. Weight



Avg. Length



0 – 17 170 2.5
17 – 26 113-142 1.0
26 – 52 57-113 1.27
* see Average
Weight Gain   for Breastfed Babies
for additional information
Gain Calculator
Age Length
in weeks* cm cm
per month
  * see the Age in Weeks Calculator

Other growth calculators

Kids Growth Chart Percentiles Calculator (height and weight for birth to age 20, body mass index for age 2-20) from These calculators don’t say which growth charts are used for the calculations.

Growth Percentile Calculator (up to 36 months) from

Growth Calculators (body mass index, growth percentile, growth velocity percentile for age 2-18) from Genentech, manufacturer of human growth hormone products.

Kid’s Height Predictor from WebMD