[en] A digital elevation model (DEM) describes the terrain relief. A proper DEM is an important data source for many of the different site description models conducted in the Forsmark region. Input data for the Forsmark DEM is elevation data for both land and sea areas of different origin and quality. No statistical analysis of the error in the Forsmark DEM is so far carried out. However, the Forsmark DEM is part of the quality assessment of the regolith depth model for the Forsmark area since it represents the upper surface of the regolith depth model. The aim of this project was to calculate the errors in different areas in the Forsmark DEM and present them in terms of general descriptive statistics. Measurements have confirmed the knowledge that the 0.25-metre DEM produced from the laser scanning measurements in the Laxemar-Simpevarp area is of very high quality. The 0.25-metre DEM was used to calculate the errors of the 10 and 50-metre DEMs, and the errors for different sea shoreline sources. These error distributions were placed randomly among points for the same data sources in the Forsmark area and used for correction of the original elevation levels. Using the corrected input data for the 10 and 50-metre DEMs and for the sea shoreline, a new DEM was produced. All other input data remained unchanged. The error for the Forsmark DEM was calculated for areas within the data sources corrected from the 0.25-metre DEM. The 0.25-metre DEM from the Laxemar-Simpevarp area was also used for a calculation of how density of input data points used in interpolation affects quality in a 20-metre DEM. Part of the input data was removed in the sea area, new DEMs were produced and compared to the existing Forsmark DEM within the areas of the removed data, to get a measure of the error in these areas of the DEM. In areas of input data for the sea shoreline, the quality of the Forsmark DEM is high. The errors within the SKB 10-metre DEM are slightly less than within the extension for the 50-metre DEM. However, the statistical analysis has revealed errors larger than 10 m within the areas of these data sources. In the sea area, the highest quality is found within the extensions of the measurements from shallow bays, the base map, and the detailed area of the measurements from the Geological Survey of Sweden (SGU). In the regional area of the measurements from the Geological Survey of Sweden, the uncertainty is much larger and errors of almost 10 m have been calculated. In the extension of the digital nautical chart/nautical chart, the uncertainty is very high with a mean error of almost 5 m, a standard deviation of a little more than 3 m, and a maximum error of more than 35 m. No error calculation was done in the lakes in the Forsmark area. However, comparing the maximum distance between points in the lakes with measurements from the sea area would suggest a quality at least as good as in the shallow bays. No error calculation was done for the inlet channel to the nuclear power plant and nor for the small areas where false depth values are placed