Currently three equations are used for calculating slope steepness factor for the revised universal soil lossequation (RUSLE); one for slopes less than nine percent, the second for slopes equal or greater than ninepercent, and the third equation that has been proposed for use in China for slopes equal or greater than 17%. The three equations have linear relationships between slope steepness factor, S and the sine of the slopeangle, q. The three equations under predict the factor, S when used on slope steepness beyond the data setsused to develop them. In addressing this problem several alternative forms of equations (linear, power, andpolynomial) were tested using field plot soil loss data gathered by several researchers in different countriesfor slopes ranging from three percent to 55 %. A single power function relating the sine of the slope angle, qto the slope steepness factor, S has been identified to be more suitable and accurate for estimating the RUSLEslope steepness factor, S.