Child Growth Percentile Calculator (LMS Approximation)
Approximate weight-for-age percentile for children.
Enter your values
Choose one of: Boy, Girl.
Enter the age in months.
Enter the weight in kg.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Weight-for-age z-score
- -0.42
- Approximate percentile
- 33.8th
- Reference median weight
- 12.9 kg
Quick answer
Growth percentile compares a child's weight to a reference population of the same age and sex using a z-score.
z = (weight - median) / SD; percentile from standard normal distribution
At a glance
| What it does | Approximate weight-for-age percentile for children. |
|---|---|
| Category | Health |
| Inputs needed | Sex, Age, Weight |
| Main output | Weight-for-age z-score |
| Formula | z = (weight - median) / SD; percentile from standard normal distribution |
| Cost | Free — no sign-up, no download |
How to use the Child Growth Percentile Calculator (LMS Approximation)
- 1Enter the child's sex, age in months and current weight.
- 2This uses a simplified reference curve for illustration and general tracking, not official WHO/CDC LMS tables.
- 3For clinical growth monitoring, use your pediatrician's official growth chart, since exact percentiles need age-specific LMS parameters.
Inputs explained
- Sex
- Choose one of: Boy, Girl.
- Age(months)
- Enter the age in months.
- Weight(kg)
- Enter the weight in kg.
Worked example
Using the values the calculator loads with:
Inputs
- SexBoy
- Age24 months
- Weight12.2 kg
Results
- Weight-for-age z-score-0.42
- Approximate percentile33.8th
- Reference median weight12.9 kg
Frequently asked questions
Why isn't this exact?
Official growth charts use detailed LMS parameters per month of age; this tool approximates the trend.
What if my child is below the 5th percentile?
Discuss with a pediatrician — it can be normal for that child, or a sign to investigate further.
What do I need to enter into the Child Growth Percentile Calculator (LMS Approximation)?
Just 3 values: sex, age, weight. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Child Growth Percentile Calculator (LMS Approximation) work out the answer?
Growth percentile compares a child's weight to a reference population of the same age and sex using a z-score. It applies the formula z = (weight - median) / SD; percentile from standard normal distribution and shows the working so you can check each step by hand.
Is the Child Growth Percentile Calculator (LMS Approximation) free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.