An algorithm for inversion of data containing information on particle size distributions is presented that is designed to be true to the input data, does not need an initial guess, does not assume a shape of the size distribution function, yields the smoothest non-negative result consistent with the input data, calculates the uncertainty of the result based on the uncertainty of the input data, and is capable of combiningdata from more than one instrument type into one inversion result. To test the algorithm, synthetic data of aircraft payloads sensitive for particle diameters Dp