A JSON file format to describe areas on growth chart PDF


Drawable Growth Charts

This repository aims to provide machine-readable definitions for growth chart files (usually PDF files). With this information at hand, software is able to overlay data points and other data on growth chart files and present it to the user.


Creative Commons License These formats are licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.


The format of choice is JSON and one JSON file defines areas on one source file, usually a PDF growth chart. The basic information element is an area object that defines an area in the parent object, which is either a page of the growth chart or another area. Areas define a point of origin (x and y), measured from the bottom left of the parent area, and the size (width and height), in numbers relative to the parent, which starts at 0,0 and has a size of 1,1.

Read the full documentation.

An experimental Mac App that reads and writes these formats is available here. A Python script that downloads all PDF files belonging to the JSON files is included and can be used as follows to download all PDF files into an existing directory PDF:

python download_pdf.py PDF

Statistics Sources

There are a lot of sources for percentile statistics out there and it is desireable to identify them easily. This can be done with a simple acronym and by specifying the year. Here are the currently used acronyms for the statistics present in this repository:

  • WHO.2006
    For the WHO charts for kids 0 - 5 years of age from the year 2006 and for kids 5 - 10/19 years of age from the year 2007. The 2007 WHO sources supplement the 2006 sources so there's no need to separate these into two acronyms.
  • CDC-infants.2000
    For the CDC charts for kids 0 - 36 months of age from the year 2000
  • CDC.2000
    For the CDC charts for kids 2 - 20 years of age from the year 2000. The two CDC sources overlap at age 2 to 3 with differing data so they have to be separated.


These are the units that should be used on charts, the bold one being the preferred one. They should be represented in the JS object notation form, e.g. length.centimeter.


  • centimeter
  • meter
  • inch
  • feet


  • kilogram
  • pound


  • month
  • year
  • day


  • kilogram-per-square-meter

Data Types

A data type unsurprisingly describes the type of data that is being represented. These should be used:

  • bodylength for body length/height, uses length units
  • bodyweight for body weight, uses weight units
  • headcircumference for head circumference, uses length units
  • bmi for the Body Mass Index (BMI), uses bmi unit
  • age for the age of the child; this can be relative, e.g. when used in the context of a measurement. Uses age unit
  • date usually used in context, e.g. in a measurement-set it means the date of the measurement
  • patient.name For the child's name (this can be used to designate data areas)
  • patient.record_id For the child's EHR id


This work was supported by a fellowship from the Swiss National Science Foundation.