The photometric accuracy of microplate readers can be checked using the calibration standard 666.013. The microplate reader standard has the same dimensions as a microplate and has windows with a 6.6 mm diameter at the same positions as the 96 wells. Neutral density glass strips with varying absorption values are located behind groups of 16 windows. All calibration standards come with a certificate of calibration.

For checking the wavelength accuracy of microplate readers microplate reader standards are available, where a neutral density glass stripe is substituted by a homium oxid glass stripe (on customer request).