Transformation efficiency is defined as the number of colony forming units (cfu) which would be produced by transforming 1 µg of plasmid into a given volume of electrocompetent cells. For example, if a 10 pg transformation with pUC19 yields 100 colonies when 100 µl of a 1:100 dilution is plated, then the cfu/µg is 1.0 x 10¹⁰ (100 cfu/10pg x 10⁶ pg/µg x 1 ml/0.1 ml plated x 100 dilution).