It costs money to improve the welfare of farm animals. For people with animals under their care, there are many factors to consider regarding changes in practice to improve welfare, and the optimal course of action is not always obvious. Decision support systems for animal welfare, such as economic cost–benefit analyses, are lacking. This review attempts to provide clarity around the costs and benefits of improving farm animal welfare, thereby enabling the people with animals under their care to make informed decisions. Many of the costs are obvious. For example, training of stockpeople, reconfiguration of pens, and administration of pain relief can improve welfare, and all incur costs. Other costs are less obvious. For instance, there may be substantial risks to market protection, consumer acceptance, and social licence to farm associated with not ensuring good animal welfare. The benefits of improving farm animal welfare are also difficult to evaluate from a purely economic perspective. Although it is widely recognised that animals with poor welfare are unlikely to produce at optimal levels, there may be benefits of improving animal welfare that extend beyond production gains. These include benefits to the animal, positive effects on the workforce, competitive advantage for businesses, mitigation of risk, and positive social consequences. We summarise these considerations into a decision tool that can assist people with farm animals under their care, and we highlight the need for further empirical evidence to improve decision-making in animal welfare.