This paper examines how the category of failure was economised and made calculable. It explores the preconditions for this shift in three stages. First, it explores how failure came to be ‘forgiven’ in both the US and the UK across the nineteenth century, how it came to be defined as something that is economic or financial, rather than personal or moral. Second, it explores the rapid growth of narrating and rating failure in the mid-nineteenth century, with particular attention to the formation of credit rating agencies from the 1840s onwards. We consider also the roles played in this process by two fortuitous technological developments: the typewriter and carbon paper for copying. Third, we examine the emergence of the calculative infrastructure, which has helped to establish an industry of attempts to forecast failure from the beginning of the twentieth century, initially on the basis of financial ratios, and more recently through the use of risk indexes. We use the term ‘calculating failure’ to describe this transformation and economisation of both the ideas and the instruments of failure, and suggest that this has significant implications for the study of strategy.