► We show people are unable to appropriately judge outcomes of moral behaviour. ► Moral beliefs have weaker impact when there is a presence of significant self-gain. ► People make highly self-serving choices in real moral situations. ► Real moral choices contradict responses to simple hypothetical moral probes. ► Enhancing context can cause hypothetical decisions to mirror real moral decisions. Moral ideals are strongly ingrained within society and individuals alike, but actual moral choices are profoundly influenced by tangible rewards and consequences. Across two studies we show that real moral decisions can dramatically contradict moral choices made in hypothetical scenarios (Study 1). However, by systematically enhancing the contextual information available to subjects when addressing a hypothetical moral problem—thereby reducing the opportunity for mental simulation—we were able to incrementally bring subjects’ responses in line with their moral behaviour in real situations (Study 2). These results imply that previous work relying mainly on decontextualized hypothetical scenarios may not accurately reflect moral decisions in everyday life. The findings also shed light on contextual factors that can alter how moral decisions are made, such as the salience of a personal gain.