This study investigated the differences between standard test methods versus numerical modelling in compression. It had the following two objectives: to compare differences between the EN and ASTM standard test results, and to determine the applicability of material tests to predict masonry wall properties. Clay bricks designed to imitate the traditional manual manufacturing process were used. For the mortar, Type II/B 32.5R cement, calcium lime CL 90 and sand were mixed at cement-lime-sand volume ratios of 1:1:6 and 1:2:9. Specimens were tested with both mortar mix designs under both the ASTM C1314-14 and EN 1052-1 methods. Experimental compressive testing using the ASTM method involved specimens 5 bricks high, with displacement measured in the vertical axis on both the front and rear faces. Compressive testing using the EN Standard involved running bond specimens 7 bricks high and two bricks long, measuring the displacement in both the vertical and horizontal directions on both faces. Numerical modelling of the small masonry wallettes was undertaken using Abaqus software, by means of a developed detailed micro-model. Input parameters for the compressive strength of the brick and mortar materials was taken from prior experimental work testing the brick units and mortar. Results were compared between the experimental prisms and numerical models derived from material tests. It was found that the modulus of elasticity of the mortar in the masonry joint could not be predicted by a mortar prism test, however, all other mechanical properties of the wall assembly could be predicted by a finite element model constructed from the individual material tests.