This study evaluates the accuracy and reproducibility of the Karsten tube and Pleyers tube methods for determining the capillary absorption coefficient of ceramic bricks and stones. Seven different brick and stone types with varying hygric properties were tested. For each type, five individual bricks were subjected to three repeated Karsten tests to assess inter- and intra-brick variability. The coefficient of variation (CV) for intra-brick measurements ranged from 5.9% to 10.6%, indicating good reproducibility. Inter-brick variability, however, was more pronounced, with CVs up to 29.3%, highlighting significant material heterogeneity within some brick types. To improve measurement accuracy, a custom-designed ring was developed that ensures a consistent and circular effective contact area, eliminating the need to manually measure the radius and reducing uncertainty in the derived capillary absorption coefficient. A comparison between the Karsten and Pleyers methods was conducted on the same brick for each type, with the bricks dried in between tests to ensure identical starting conditions. The results from both methods were next compared to a reference value obtained from a standard water uptake test. The findings show that the Pleyers tube does not yield more accurate results than the Karsten tube including analytical description and is more challenging to handle. Given its ease of use, broad applicability, and sufficient accuracy, the Karsten method is preferred. Overall, this research supports the use of the Karsten tube, especially when combined with the ring, as a robust in-situ method for evaluating the capillary absorption coefficient of masonry materials.