A method is described for calculating approximate electron ranges. The method uses a simple but less accurate analytic expression for electron range derived in calculations of cascade showers. An energy dependent correction factor is then applied to give reasonable agreement with calculations using the more rigorous theoretical treatment employing the continuous slowing down approximation. It is shown that, if energy dependent correction factors are derived for one element (e.g. aluminium), then these same correction factors can be used to compute electron ranges in other materials that are not too different in atomic weight.