Weight Percentile (Approximate)
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Very rough percentile placement — always use official CDC/WHO growth charts for real tracking.
This estimates a weight-for-age percentile using a simplified reference curve (a handful of age anchor points with linear interpolation between them, assuming a roughly normal distribution). It is not the official CDC or WHO growth chart — those use much finer-grained, sex-specific data collected from large population studies. This tool is meant to illustrate roughly where a weight falls relative to typical values at a given age, not to track a child's actual growth. Always use your pediatrician's official chart for real tracking.
z = (weight − reference mean at that age) ÷ reference standard deviation → percentile = Φ(z) × 100