The calculation of the cost of mastitis is complex and has been associated with multiple factors: the disease (prevalence, severity, effects, aetiology, concurrent disorders, etc.), the animal (lactation status, age, productive level), the setting (treatment protocols, methods of prevention, elimination, management), and prices (value of different expenses, price of milk, penalties and premiums). The complexity and heterogeneity of the many variables involved and their interactions promote duplication of effects and errors, and affect the credibility of results. When trying to calculate the cost of mastitis at field level, simplicity and clarity are.