GUIDE
Wondering if your baby's on track? Plug in their measurements and see for yourself.
Supports both WHO and Fenton growth charts — totally free, and your data stays right here in your browser.
Save measurements over time
“We keep close tabs on whether your child is growing appropriately since so much development and growth goes on in those first few years.”
Dr. Minh-Y Canh, DO, Pediatrician, Cleveland ClinicOptional — lets us calculate age from checkup dates.
Plotted on WHO Child Growth Standards
For term babies, 0–60 months
Growth charts compare your baby's size to thousands of other healthy kids the same age and sex. There's no single "normal" number — instead, you get percentile curves, which are just smooth lines showing how children at each percentage rank tend to grow over time.
So if your baby is at the 40th percentile for weight, that means 40% of babies their age weigh less and 60% weigh more. There is no single "right" percentile. What really matters is that your baby follows their own curve over time — not where that curve happens to be.
Go with this for <span className="text-foreground font-medium">term babies</span> (born at 37+ weeks). WHO charts cover birth to 5 years and are based on a huge global study of healthy, breastfed kids. This is what most pediatricians pull up at your regular checkups.
This one's for <span className="text-foreground font-medium">preterm babies</span> (born before 37 weeks). Fenton charts track growth by gestational age from 22 to 50 weeks, so NICUs and parents can follow catch-up growth properly. The 2025 third-generation update excluded infants with abnormal fetal growth, making the benchmarks even more accurate.
If your baby was born before 37 weeks, standard WHO percentiles can be misleading — even alarming. A preemie plotted on a full-term chart will almost always look small, because the chart wasn't designed for them. That's not a growth problem. It's a chart problem.
Fenton growth charts solve this by using preterm-specific data, tracking weight, length, and head circumference by gestational age from 22 to 50 weeks. Tinylog supports both WHO and Fenton charts in the app, so you can plot your baby's growth on the right curve — whether they were born at 28 weeks or 40. For more on what preemie parents should look for in a tracker, see our guide to preemie-friendly baby trackers.
One measurement is just a snapshot — it tells you where your baby is today. But when you plot measurements over time, that's where the real story is. Percentiles are a screening tool, not a diagnosis.
Your pediatrician is looking at two things: (1) is your baby within the normal range (3rd-97th percentile), and (2) are they following their own curve without big jumps up or down. Crossing a percentile line here and there — especially during a growth spurt or after being sick — is totally normal.
Log weight, length, and head circumference after each visit. You'll get percentiles on WHO and Fenton charts, see trends at a glance, and can share a growth summary with your pediatrician.
Growth charts are helpful, but they're not a substitute for real medical advice. If something worries you, reach out to your pediatrician.
Baby Growth Percentiles — What the numbers on the chart mean
Baby Dropped Percentiles — When to worry about percentile changes
Should You Track Growth at Home? — Pros, cons, and how to do it right
