Frequently Asked Questions
Seven common questions about the baby growth percentile calculator. Reach us at comsamo84@gmail.com for more.
Frequently asked questions
How are the WHO and KCDC 2017 charts different?
Since 2017, Korea (KCDC and the Korean Pediatric Society) adopted the WHO standard verbatim for 0-24 months, so the two charts are effectively identical inside this tool’s window. KCDC uses Korean-specific data after 24 months, but that range is outside this calculator’s scope.
How do I enter data for a preterm baby?
For babies born 3+ weeks early, use corrected age (calculated from the due date) up to about 24 months. Since this calculator works in calendar months, simply enter the due date as the birth date to get the corrected-age percentile; many parents save both rows for comparison.
Is it OK if the percentile wobbles by a band or two?
Wobble within one percentile band is common due to home-measurement noise and feeding variation. Concern usually starts when a baby consistently crosses two major bands (e.g. P75 → P25) over multiple readings spaced 2+ weeks apart with the same scale and time of day. Trend matters more than any single point.
Weight is P30 but length is P70 — is the baby underweight?
Underweight or overweight should be judged via weight-for-length, not a single chart. This tool shows weight, length and head circumference separately; ask your pediatrician for the weight-for-length plot at well-baby visits. A weight-for-length above the 85th percentile is the usual overweight flag; below the 15th is the underweight flag.
My baby’s head circumference grew quickly — is that dangerous?
Head circumference reflects brain growth and warrants attention when it changes faster than weight/length. First, re-measure three times and average, since a 0.5-1 cm variation from tape angle is common. If the average still crosses two bands or shows asymmetry, ask your pediatrician — a neurodevelopmental check may be appropriate.
Is there a separate chart for twins?
Neither WHO nor KCDC publishes a twin-specific chart. Clinicians use the singleton reference while accounting for gestational age, birth weight and corrected age. Twins often grow a touch slower in the early months, so treat this tool’s output as a reference and rely on individualized pediatric assessment.
Where is the measurement data stored, and is it safe?
All baby info and measurement history are kept only in your browser’s localStorage and never sent to a server. Data persists on the same device and browser, and clearing browser data clears the history. Multi-device sync is intentionally not provided, so no measurement leaves your machine.