In ocean models, submarine melt of ice shelves is parameterized based on the heat budget at the ice–ocean interface. The heat budget includes the ocean heat transport, the heat conducted into the ice, and the heat available for melting. Here we compare three different approaches to estimating the heat conduction into the ice. We show that the most used approximation is not the most accurate one: it overestimates the melt by up to 25 % compared to the more accurate approximations.