The IPT-calculator calculates the chances for players to win a game, set or match at any stage during a match. A prediction-tool that can be used to help to predict/forecast the outcome of a tennis match at any stage during the match. A fine tool for anyone who is interested in the dynamics of In Play Event Prediction Calculations. The application just calculates chances based on variables given by the user. The used variables are: What percentage do each player have to win a point at their own service (WOS). Which is indirectly the base for bookmaker-odds as well, as this percentages determines the strengths of players. The bigger the differences in WOS-percentages between the players, the bigger the difference of the chance of winning the match.