About the Digital Growth Charts API

Evaluating and recording a child’s growth has traditionally involved plotting measurements on paper growth charts which have been developed using complex data sets and statistics.

To support the drive to digitise healthcare RCPCH has, for the first time ever, developed a Digital Growth Charts API to accurately calculate centiles for a child’s height, weight, head circumference and BMI.
Why is the College producing this API?

Clinical assessment of children’s growth is hard, because children do not grow linearly. They have growth spurts and plateaus, and because of this their height or weight at any given age is clinically informative only if compared with other children of the same age, to see whereabouts they lie in the ‘normal’ range.

The science behind this process is well established and was pioneered and popularised in the 1990s by statisticians and paediatricians, who created paper lookup charts which enabled the early detection of deviations from normal growth. For decades the state of the art has been plotting growth onto charts printed on paper or card, and many parents will be familiar with the paper growth charts in their child’s Red Book.

Now, however, this paper workflow is outdated and incompatible with the expectation of digital healthcare, personal health records, apps and the Internet of Things.

The challenge with switching to growth charts in a digital form is that the maths behind these charts is complex and the dataset they rely on for calculations is difficult to understand. For this reason, digital growth charts have not been developed by vendors of electronic patient records (EPRs), simply because they cannot justify the upfront costs, difficulty, and clinical risk.

By developing the calculations as a national, web-based ‘service’ API (Application Programming Interface) RCPCH has fundamentally changed the paradigm.

No longer will EPR vendors have to separately develop growth chart functionality, at great cost, and slowly. Instead, the RCPCH Digital Growth Charts API provides a decoupled web-service approach, which allows us to ‘do once and share’ – and it has created a single, national, Royal College-validated system for accurate growth charts and related calculations, which EPR suppliers can build into their products at low cost.

By building a complex ‘infrastructural’ calculation like this into a REST API, RCPCH has provided the kind of fundamental basis for innovation in healthcare that the rest of the tech world has benefited from for nearly two decades – pure service APIs like Mapping (e.g. Google Maps), Telephony (e.g. Twilio) and Payments (e.g. Paypal/Braintree) – all of which wrap difficult problems in a low-cost, easy-to-use layer, vastly reducing the cost of innovation, and speeding up development spectacularly.

While the project looks from the outside quite simple, the doors it opens are vast. Using the RCPCH API, even low-computing-power ‘Internet of Things’ devices can benefit from accurate measures of growth, delivered straight to the user. Applications can easily integrate growth charts into their clinician- or parent-facing user interfaces, with minimal complexity and cost, driving up standards everywhere.


  • Produced by a multidisciplinary group of members and other experts from clinical paediatrics, health informatics, statistics and programming, as well as childhood growth and nutrition specialists, health visitors and information governance experts
  • Access includes RCPCH-created guidelines and advice for health professionals aiming to improve standards of growth measurement and assessment
  • Easy creation of apps and interfaces that will give clinicians accurate data to improve care and give access to their children’s growth records online
  • Access to ongoing maintenance and future development
  • The ability to receive longitudinal growth data of individual children, which will enable the API to map children’s growth pattern, trajectory and thrive lines
  • Standardised open data format for all growth references, allowing research groups to develop specialist or localised growth charts using third party data sets
  • Pending accreditation from Medicines and Healthcare Products Regulatory Agency

Technology and standards

[This is what your IT team needs to know]

The took has been developed as a national, web-based service API using the following technology and against the following standards: 

  • Python & Flask, Javascript
  • React (for demo client), Semantic UI
  • openAPI3.0, Postman
  • ISO27001, DCB0129 and DCB0160
  • Azure - cloud infrastructure services
  • API management layer

Subscriptions and pricing

Tier Description £ per month* Max API calls per month Support
Free For the hobbyist or developer looking to experiment with the API £0 250 Forum
Basic For small organisations - features increased API call quota £100 2,000 Forum + agreed technical support
Intermediate For intermediate usage of the RCPCH growth charts £250 5,000 Forum + agreed technical support
Advanced For mid-size organisations - features increased API call quota £500 10,000 Forum + agreed technical support
Enterprise Features negotiable quota and rate limits Price on application Negotiable Negotiable

*All prices are subject to VAT. Price for technical support to be discussed and agreed with the Commercial team

Contact us to find out more

Explore the demo and API, and contact us

Have a question about digital growth charts or would you like to sign up to one of our subscription plans? Please complete our Digital Growth Charts API enquiry form

Want to read more about the products and how the API works? See a demo? Access our Digital Growth Charts API demo