This calculator works best on desktop computers. For mobile devices use landscape mode. Please allow for tolerances as LRV numbers are calculated as whole numbers whereas the Contrast is in percentage format.

LRV stands for Luminance Reflectance Value

TGSI stands for Tactile Ground Surface Indicator

The contrast formula used in the app for Australia is the Bowman-Sapolinski Equation with LRV readings which are to be obtained as noted in AS1428.1-2021 is:

125(Y2-Y1) / (Y1+Y2+25)

where Y2 is the LRV of the lighter area and Y1 is the LRV of the darker area.

The recommendations vary from 30% to 60% based on the element. Please refer to AS/NZ1428 suite of Australian Standards for details.

Note that LRV is on a scale of 0 to 100 (black to white), however both white and black are never absolute and therefore in reality B1/Y2 never equals 100 and B2/Y1 is always greater than 0.