In this study, the interpretation of float-sink test data by simple equations on coals of different origins with respect to sulfur content has been investigated. Primarily, the cumulative weight and sulfur content of the floating fraction have been determined for each coal in all relative densities tested. For deriving of the equations, the recoveries of both non-sulfur and sulfur compounds in cumulative floating part have been calculated. Then, the relationship between the recoveries and relative densities has been stated as simple equations and the calculated values from equations have been compared with the experimental results. Furthermore, it has been found that these types of equations are suitable for the interpolation of sink-float data. The results reveal that the float-sink test results can be stated by simple equations relating to the sulfur content. (C) 2002 Elsevier Science B.V. All rights reserved.