This paper focuses on how to calculate diluted earnings per share (DEPS) when a firm has outstanding employee stock options (ESOs). Three possible methods are described and compared. The first is the current International Accounting Standard 33 – Earnings Per Share (IAS 33) approach which is based on the intrinsic value of the ESOs. The second method, advocated by Core et al. (2002), is very similar to that of IAS 33 but instead of the intrinsic value uses the fair value of the outstanding options. This paper derives an alternative method which adjusts the earnings for the year by the change in fair value of the outstanding ESOs, with no adjustment to the denominator in the DEPS calculation. The three methods are compared using a simple firm. The earnings adjustment method best describes the change in economic value of the current shareholders, the fair value is more useful in predicting future profits, and the intrinsic value method appear to provide no additional information to that already contained in the other two measures. The earnings adjustment method has a further advantage in that it provides an identical result at a DEPS level to that which would have been obtained if the ESOs were cash-settled and treated as liabilities in terms of IFRS 2. Thus using this method will improve comparability as cash-settled and equity-settled options have a very similar economic effect on current shareholders.