Enter the data into a new sheet in your workbook. You can copy the data but will need to use Paste > Special (text) to convert it from html. Write a macro to determine the Absorbance (A) of a sample from the % Transmittance (%T). The formula to use to determine absorbance from %T is = - log(%T/100). Place the macro under a button. Save your spreadsheet as a Macro Enabled Worksheet. %T A 24.9 73.7 18.7 80.4 8.54 24.4 76.4 10.7 97.1