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Our centile calculators produce customised birthweight centiles using the principles of the GROW (Gestation Related Optimal Weight) method.
See References and Related Literature for further information.

The calculators are continually being updated for different populations and countries, depending on the availability of databases from which coefficients can be derived. Below is a list for some of the currently available countries.

The tools are free and available as one of two types of applications:

  • Individual centile calculator - for day-to-day use, to calculate birthweight centiles one at a time. Now available as a web based application.
  • Bulk centile calculator - to derive multiple centiles for research or audit purposes; developed in Excel spreadsheet format (download version history)

To receive a link or copy, please write to the Gestation Network - with the following information:

  1. Name, affiliation, and brief note about the intended use (clinical, audit, or area of research), to help us keep refining these applications
  2. Type of calculator required (individual or bulk), and for which country.

Is your country not represented? We welcome anonymised databases to derive coefficients for additional countries / populations. Please write to for further details.


GROW software makes calculations on the basis of published principles and formulae, and is released only after rigorous testing for quality assurance.
However Gestation Network or the Perinatal Institute cannot accept responsibility for clinical diagnoses or decisions made on the basis of the software. For more information, see our terms and conditions of use.


© Gestation Network 2017