Fracture toughness of a 70-mm-thick plate of the aluminum alloy 7475-T7351 was measured with short-bar and compact specimens. The compact specimens with thicknesses of 25 and 38 mm and the short-bar specimens with thicknesses of 12.5, 25, and 50 mm had T-L orientation and were machined at different distances from the surface. Different heats of the same alloy tested in T-L and L-T orientation furnished a series of fracture-toughness values ranging from 40 to 60 MPa m^1/2 in increments of approximately 2 MPa m^1/2. For each of the selected heats K_Ic and K_IcSB was determined. Both fracture toughness test methods confirmed a fracture-toughness profile through the thickness direction of the plate. The fracture toughness was highest in the midsection and lowest in the surface region of the plate. Increasing fracture toughness with increasing specimen size was found for both testing methods, but K_IcSB was consistently higher than K_Ic for specimens of identical thickness. The difference between K_Ic and K_IcSB increases with increasing fracture toughness. From the results it is concluded that the through thickness variation of K_Ic is not the main reason for the higher short-bar values.