A growth percentile shows how your baby compares to other babies of the same age and gender. If your baby is at the 75th percentile for weight, it means 75% of babies weigh less and 25% weigh more. It's a comparison tool, not a 'score' - there's no 'best' percentile.

The World Health Organization (WHO) growth standards describe how healthy children should grow under optimal conditions. They're based on a multinational study of breastfed children and are the international standard for monitoring infant growth from birth. Most countries now use WHO standards for children under 2.

Most healthy babies fall between the 15th and 85th percentiles. The 5th to 95th range is considered the 'normal' range. What matters most is consistent growth along your baby's own curve, not the specific number. A baby consistently at the 20th percentile is perfectly healthy.

No! The 50th percentile is just the median (average), not a goal. Half of all healthy babies are below the 50th percentile by definition. What matters is that your baby follows their own growth curve consistently. Genetics play a huge role - smaller parents often have smaller babies.

Consult your pediatrician if: 1) Your baby drops across two major percentile lines (e.g., from 75th to 25th), 2) Percentile is below 3rd or above 97th, 3) Weight and height percentiles are very different (e.g., 90th weight, 10th height), or 4) There's a sudden change in growth pattern.

Head circumference reflects brain growth. Pediatricians measure it to ensure proper neurological development. A head that's too small or too large, or that's growing too slowly or quickly, may warrant further evaluation. It's measured at every well-baby visit in the first 2-3 years.

Follow your pediatrician's schedule for well-baby visits (typically 2 weeks, 1, 2, 4, 6, 9, 12, 15, 18, and 24 months). Medical scales and measuring equipment are most accurate. Home measurements can complement but shouldn't replace professional check-ups.

Weight-for-age compares your baby's weight to all babies of the same age. Weight-for-height (not used in this calculator) compares weight to babies of the same height, which can identify if a baby is under/overweight regardless of their overall size. Both are useful metrics.

This calculator uses official WHO median values and estimates percentiles using z-score approximations. For official clinical assessment, always consult your pediatrician who has access to complete WHO charts. This tool is for educational reference and tracking trends.

Developmental milestones are skills most children can do by a certain age - like sitting, crawling, walking, and talking. Our calculator shows expected milestones for your baby's age. Remember, milestones have ranges; some babies walk at 9 months, others at 15 months - both are normal.

For premature babies (born before 37 weeks), pediatricians often use 'corrected age' - subtracting the weeks of prematurity from the baby's actual age. For example, a 4-month-old born 8 weeks early would be compared to a 2-month-old's standards. Specialized preterm growth charts also exist.

Boys and girls have different growth patterns. On average, boys are slightly heavier and longer at birth and maintain this difference throughout childhood. Using gender-specific charts ensures accurate comparisons. This calculator automatically adjusts for gender.

Growth charts have curved lines representing percentiles (3rd, 15th, 50th, 85th, 97th). 'Crossing lines' means a baby moves from one percentile zone to another over time. Dropping across two major lines (e.g., from above 50th to below 15th) may indicate a growth concern that should be evaluated.

Breastfed babies often grow faster in the first 3-4 months, then slower from 4-12 months compared to formula-fed babies. WHO charts (which we use) are based on breastfed infants and are the recommended standard. Some older charts (CDC) were based on formula-fed babies.

Yes! Click the download button in the results panel to save a text report with your baby's measurements, percentiles, and the date. You can use this to track progress over time or share with your pediatrician.