A new tool for standardized calculation of solar collector performance has been developed in cooperation between SP Borås Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance for a number of representative cities in Europe on the basis of parameters from collector tests performed according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that intend to use it for conversion of collector model parameters derived from performance tests, into a more user friendly quantity i.e. the annual energy output. Energy output both per m2 and per collector module can be calculated.