Baby Growth Percentile Calculator (WHO 0–24 Months)
Enter the babys sex, age, length, and weight to get percentiles and z-scores for two WHO Child Growth Standards indicators: length-for-age and weight-for-length. Calculations use the official WHO LMS tables (daily precision).
What this tool covers
- ✅ Length-for-age, 0–24 months — detects stunting.
- ✅ Weight-for-length, 45–110 cm — detects wasting & overweight.
- ❌ Does not compute weight-for-age → use the Baby Weight Percentile Calculator.
- ❌ Does not compute head-circumference-for-age → use the Head Circumference Percentile Calculator.
Calculate now
1. Length-for-age
2. Weight-for-length
Looking for weight-for-age?
The third WHO indicator — weight-for-age — is computed by our separate sibling tool so each tool stays focused and accurate:
Worked examples (verified)
Example 1 — Boy, 12 months, length 76.0 cm, weight 9.5 kg
Length-for-age: z-score +0.11 → percentile 54.4 (normal).
Weight-for-length: z-score −0.26 → percentile 39.9 (normal).
Example 2 — Girl, 6 months, length 65.0 cm, weight 7.0 kg
Length-for-age: z-score −0.33 → percentile 37.0 (normal).
Weight-for-length: z-score −0.13 → percentile 45.0 (normal).
Example 3 — Newborn boy (0 months), length 50.0 cm, weight 3.4 kg
Length-for-age: z-score +0.06 → percentile 52.4 (normal).
Weight-for-length: z-score +0.24 → percentile 59.5 (normal).
Example 4 — Girl, 24 months, length 87.0 cm, weight 12.0 kg
Length-for-age: z-score +0.19 → percentile 57.4 (normal).
Weight-for-length: z-score +0.26 → percentile 60.4 (normal).
Frequently asked questions
How is this calculator different from the Baby Weight Percentile Calculator?
This calculator computes two WHO indicators: length-for-age (detects stunting) and weight-for-length (detects wasting and overweight). The Baby Weight Percentile Calculator computes the third indicator, weight-for-age. All three complement each other and use the same official WHO LMS tables.
Why is it only for babies 0–24 months?
WHO standards distinguish measurement methods: ages 0–24 months are measured lying down (length-for-age), while ages 2–5 years are measured standing (height-for-age) with different tables. This tool uses the 0–24-month length-for-age tables to match the measurement method.
How is the z-score computed?
Using the WHO LMS method: z = ((X/M)^L − 1) / (L×S), then percentile = the cumulative normal distribution function of z times 100. The L, M, and S values come from the official WHO expanded tables — daily precision for age (0–730 days) and per 0.1 cm for length (45–110 cm).
What do z-scores of −2 and +2 mean?
These are the WHO standard cutoffs: z below −2 means stunting (for length-for-age) or wasting (for weight-for-length); z below −3 means severe and needs prompt consultation. For weight-for-length, z above +2 means at risk of overweight and z above +3 means obesity. The range −2 to +2 is considered normal.
Is this result a medical diagnosis?
No. This tool is a screening tool based on WHO standards, not a substitute for a diagnosis by a doctor, midwife, or nutritionist. If results fall outside the normal range, consult a health facility or local health post.
Why is weight-for-length important?
Because weight-for-age alone can be misleading: a baby who is short but chubby can look normal. Weight-for-length compares weight against the babys own length, so wasting and overweight are detected more accurately.
How do I measure a babys length correctly?
Measure lying down using an infantometer or measuring tape: head against the headboard, both legs straightened, heels against the footboard. Record to 0.1 cm precision. A measurement error of even a few centimeters can change the z-score significantly.
How accurate are the tables used?
The tables come from the official WHO Child Growth Standards expanded files (MGRS 2006 study): 731 daily rows (days 0–730) × 2 sexes for length-for-age and 651 length points × 2 sexes for weight-for-length. Row 732 in the WHO table (day 731) is height-for-age — 0.7 cm lower — and is deliberately excluded since this tool uses length-for-age. Every LMS cell was revalidated against the official WHO field tables before publication.
⚠️ Not medical advice
This calculator's results are information/screening based on WHO growth standards and not a medical diagnosis. Every child's growth is influenced by many factors (genetics, nutrition, health). Always consult results outside the normal range — or any concern — with a doctor, midwife, nutritionist, or health post.
Methodology & data sources
| Indicator | Length-for-age & weight-for-length, WHO Child Growth Standards (MGRS 2006) |
|---|---|
| Range | Age 0–24 months (0–730 days); length 45.0–110.0 cm |
| Tables | File "z-scores: expanded tables" (xlsx) official from cdn.who.int — machine-copied, then 12 anchor cells validated against the official WHO field tables |
| Formula | z = ((X/M)L − 1) / (L×S); percentile = Φ(z) × 100 |
| Age mapping | months → days = round(months × 365.25/12); length → index = round((cm − 45) × 10) |
Category cutoffs follow WHO standards: stunting/wasting when z < −2 (severe when < −3); overweight when z > +2 and obesity when z > +3 (weight-for-length only).
Related tools
- Baby Weight Percentile Calculator — weight-for-age 0–24 months (WHO).
- Head Circumference Percentile Calculator — head-circumference-for-age 0–5 years (WHO).
- All nrtechstudio.com tools
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