Enter your infant, baby or toddler's age, sex, weight and length/height to estimate their BMI and how it compares to WHO BMI-for-age standards.
A BMI-for-age percentile above the 97th is generally the threshold pediatricians use for "overweight" in babies and toddlers, but a single reading is rarely a concern on its own — babies naturally carry more body fat than older children, and chubby limbs at this age are often completely normal. Talk to your pediatrician if you're worried, especially if the trend keeps climbing over several checkups.
A percentile below the 3rd is the typical threshold for "underweight," but again, context matters — a baby who has always tracked near the lower end of the curve and is otherwise feeding, growing and hitting milestones normally is usually fine. A sudden drop across percentiles is more worth flagging to your pediatrician than a low but steady one.
Babies and toddlers naturally have a higher, more variable BMI than adults or older kids, and it typically peaks around 9–12 months before gradually leveling off through the toddler years. A single high reading, especially in a chubby, active, well-fed baby, usually isn't cause for concern — but persistent, sharply rising percentiles are worth a conversation with your pediatrician.
The formula (weight divided by height squared) is the same, but the interpretation isn't — adult BMI uses fixed cutoffs, while baby and toddler BMI is compared to WHO BMI-for-age percentiles that account for how body proportions naturally shift with age and sex during the first years of life.
Yes — this calculator covers ages 0–60 months, so "infant," "baby" and "toddler" are all the same age range here, just different words for the same stage. Enter the exact age in months and the WHO BMI-for-age standard applies the same way.