Sign up for NPL updates
Sign up for NPL updates

Receive regular emails from NPL to get a glimpse of our activities and see how our experts are informing and influencing scientific debate

Gas reference materials

Gas metrology software

Analysis of your data


GravCalc2 is Windows-based software that calculates the amount fraction and uncertainty of all components in gravimetrically prepared gas mixtures using the method described in ISO 6142. The programme can be used for any gas mixture.

A copy of the program user guide can be downloaded free of charge here.

For further information about GravCalc2, or to request a quotation, please contact us.


XLGENLINE is MS Excel-based software that allows the user to perform generalised least squares (GLS) regression analysis that is fully compliant with ISO 6143. XLGENLINE calculates the amount fractions and estimated uncertainties of 'unknown' samples, displays a plot of the fitted regression function, and outputs the parameters of the fit (gradient, intercept, covariance, etc.).

The software, which can also be used for ordinary least squares (OLS) regression analysis can be downloaded free of charge from the Software page.

Don’t see what you are looking for? Our diverse skill set enables us to provide bespoke solutions. Please contact us to discuss your requirements.

Contact us

Work with us

Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success.
Contact our Customer Services team on +44 20 8943 7070