Estimating the contribution of ice sheets to sea level change is a major goal of glaciologists and of high interest for the public. For this purpose we analyse altimeter data of different satellite-borne satellites with a main focus on CryoSat-2 and estimate by this the volume change and as a final product the mass change using a firn densification model. For the assessment of the contribution of ice sheets to sea level change robust, consistent processing, as well as the estimation of uncertainties is important. There are numerous sources for uncertainty, ranging from instrumental errors, different processing approaches towards the interpolation between sparsely distributed data. This presentation focuses on the present-day ice-volume changes of the Greenland and Antarctic ice sheets. Based on five years (January 2011 to January 2016) of CryoSat-2 data acquisition we derived elevation change maps and finally volume and mass change estimates for both ice sheets. We will present a set of estimates derived from different processing approaches and interpolation methods. Additional we will compare our results to elevation change rates obtained from ICESat data covering the time period from 2003 to 2009. In contrast to our study of 2014 we extended the time series of CryoSat-2 by two years, used the new data release 34 of ICESat and implemented the output of the firn densification models of the Institute for Marine and Atmospheric research Utrecht (IMAU). The new results will be presented and compared.