A file conversion system provides a plurality of network computing platforms, each computing platform having one or more conversion engines executing thereon. When a file is to be transferred, a plurality of destination file types is determined. If all destination file types are different from the file's current type, the file is converted to a file having a type corresponding to one of the destination file type. If the file needs to be converted, then a conversion path, potentially passing through multiple conversion engines associated with a least conversion cost is chosen to perform the conversion. The file is sent to the computing platform on which the conversion engines associated with the least cost conversion are executing. Moreover, the least cost conversion can take into account the destination cost. Conversion costs are determined using a table of costs for performing various conversions. The table stores both static costs which remain constant during system operation and dynamic costs which vary with system operation.