2026 Baby Growth Percentile Calculator
Back from the pediatrician with a sheet of numbers? Enter your baby's age, weight and height to see their percentiles in plain English. Free, no sign-up, for ages 0-24 months. Educational only — not medical advice.
Weight percentile
Enter a value
WHO avg: 16.1 lb for a 6.0-mo girl.
Height percentile
Enter a value
WHO avg: 25.9 in for a 6.0-mo girl.
Head percentile
Enter a value
WHO avg: 16.8 in for a 6.0-mo girl.
Saved to this browser — your last entry is remembered. Using WHO reference data with chronological age.
Growth by age (0-24 months)
Average weight, length and milestones for each month — and when to check in with your pediatrician.
Understand each measurement
⚖️Baby Weight Percentile
A baby weight percentile compares your little one's weight to other babies of the same age and sex. If your baby is in t…
📏Baby Height Percentile
A baby height (length, for babies measured lying down) percentile compares your baby's length to other babies of the sam…
🧠Baby Head Circumference
Head circumference is measured around the widest part of your baby's head — just above the eyebrows and ears — and is on…
📊Baby BMI / Weight-for-Length
BMI is not used the same way for babies as for adults. For children under 2, pediatricians use weight-for-length — compa…
How baby percentiles actually work
At every well-baby visit, your pediatrician measures three things: weight, length and head circumference. Each measurement is plotted on a growth chart — a set of curves built from thousands of healthy babies. The curves are labeled with percentiles: the 3rd, 15th, 50th, 85th and 97th are the common reference lines. The 50th percentile is the median, the exact middle. If your baby's weight lands on the 50th line, half of babies their age weigh more and half weigh less.
Here is the single most important idea, and the one new parents most often miss: there is no "good" or "bad" percentile. A baby in the 10th percentile is not behind, and a baby in the 90th percentile is not ahead. Both are simply different, healthy sizes — the same way some adults are 5'2" and others are 6'2". What pediatricians actually watch is the trend. A baby who has tracked the 25th percentile since birth is the picture of healthy, steady growth. The thing that gets a doctor's attention is a baby who jumps or drops across several percentile lines between visits, because that change — not the number — can be worth investigating.
Measurements at home are also less precise than you might think. A wiggly baby on a home scale, a length read off a tape measure, the weight of a diaper — small errors add up to a percentile or two. That is exactly why one reading should never set off alarm bells. Use BabyPercent to understand the numbers from your checkup and to feel calmer between visits, not to make decisions. It cannot replace the trained eye and accurate scale at your pediatrician's office.
Reminder:BabyPercent shows reference averages for education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. If you are ever worried about your baby's growth, feeding or development, call your pediatrician — that is always the right move.
Compare baby growth trackers
Review how BabyPercent differs from popular growth chart apps before choosing a tracker.
Open comparison guidesFrequently asked questions
What is a baby growth percentile?
A percentile compares your baby to other babies of the same age and sex. If your baby is in the 70th percentile for weight, they weigh more than about 70 out of 100 babies their age. It is a position on a curve, not a score — being in any percentile from 3 to 97 is generally considered a normal, healthy range.
Is a low percentile bad?
Not on its own. A baby who has tracked steadily along the 10th percentile since birth is usually growing perfectly well. Pediatricians worry far more about a sudden change — a baby crossing several percentile lines up or down — than about the number itself. This tool is educational only and not medical advice; discuss any concerns with your pediatrician.
Which chart does BabyPercent use — WHO or CDC?
BabyPercent provides both WHO and CDC reference data so you can compare. The WHO charts (based on healthy breastfed babies from six countries) are recommended by the CDC and AAP for ages 0-24 months. CDC charts are based on a US reference population. The values shown are reference averages for general understanding, not an official medical chart or diagnosis.
Is BabyPercent free?
Yes — completely free, no sign-up, no app. Your last entry is saved in your own browser so it is ready every month when you come back from a checkup. No data is ever sent to any server.
What measurements does BabyPercent track?
BabyPercent tracks three core growth measurements: weight, height (length), and head circumference. These are the same three measurements your pediatrician takes at every well-baby visit. We also provide weight-for-length interpretation (the baby equivalent of BMI) as an educational reference.
Does BabyPercent work for premature babies?
Yes — the calculator includes an option to adjust for prematurity. For babies born before 37 weeks, pediatricians use adjusted (corrected) age until about 24 months. Select your baby's prematurity level in the tool to get percentiles based on their adjusted age. Always discuss prematurity growth concerns with your pediatrician.
What do I do if my baby is not on the chart?
If your baby's weight or length falls below the 3rd or above the 97th percentile, do not panic. These are reference curves, not pass/fail lines. A single reading tells you very little. Call your pediatrician if your baby crosses several percentile lines between visits, is not feeding well, has very few wet diapers, or if your gut tells you something is off.
Can this replace my pediatrician?
No. BabyPercent is for education and peace of mind only. It is not medical advice and cannot diagnose anything. Your pediatrician measures your baby accurately with calibrated tools, plots the trend over time, and considers your whole family's health history. Always consult them about your child's growth.