OBJECTIVE: To offer scientists and policy makers a tool for standardized indirect/productivity cost estimations that (a) can be adapted to different contexts and (b) allow for the comparison and transfer study results within and between countries. METHODS: MICE consists of an Excel spreadsheet, a handbook, and documentation specifying the data sources. It computes the age- and sex-specific unit costs per day or year of lost work in the paid and unpaid work sector, for the general or the employed population. Due to its flexibility it can be adapted to national guidelines for economic evaluation as well as to different perspectives (e.g. societal or employer). The human capital approach or the friction cost method can be chosen. For the valuation of lost productivity, different approaches can be selected, e.g. labor costs for the paid work sector or substitution costs for the unpaid work sector. The reference year is 1999 and can be simply updated. MICE is available and has been successfully applied to The Netherlands and Germany with other countries to follow. RESULTS: For a Dutch/German inhabitant aged 33, the unit costs for the loss of one actual working day of paid work are €83 / €104 for females and €179 / €180 for males (basis: labor costs, elasticity of annual labor time versus labor productivity=1). The respective unit costs for a Dutch/German employee are €126 / €149 for females and €193 / €202 for males. CONCLUSIONS: MICE enables a standardized and precise estimation of indirect costs in different countries. Its feasibility, transparency, and flexibility have been shown in several studies. MICE provides a useful tool for multinational studies. It not only improves the comparability of national and international study results, but also increases their transferability.