This is a calculator for evaluating one's equity in a poker tournament, and in particular for deciding whether to rebuy. Its use is described in the documentation page. It is based on a stochastic model, which is known not to be realistic if there is both more than one prize and more than one short-stacked player. Its calculations are made precisely on the basis of this model, and are, to the best of my knowledge, correct. However, no warranty is offered. We recommend that you test it before using it for real poker tournaments.