Fan Calibration Variable Calculator

The ATTMA Building Compliance Tester Association has developed the following tool to calculate fan calibration variables, particularly useful for new Retrotec Fans which use Polynomial variables.

Enter appropriate numbers and units from your calibration certificate and the unit of measure you wish the calibration variables to be displayed for entry into your air tightness testing software. For the vast majority of fans leave the Polynomial check box unticked as this is specifically for the B4 and smaller range plates on the Retrotec 5000 and 6000 series fans.

No. of Rings/Ranges No. Readings Volume Flow Rate
Certificate Software




This tool has been designed for use when the calibration variables have not been provided by your calibration laboratory. An assumed air density of 1.2kg/m3 has been used within the calculator. ATTMA takes no responsibility for errors.