Performance measurements of large-diameter circular saws were conducted on eight different carbonate rocks in marble factories located in some areas of Turkey. Rock samples were collected from these factories for laboratory tests. Uniaxial compressive strength, tensile strength and impact strength were determined in the laboratory. The brittleness of B-3 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), the brittleness of B-5 (the product of percentage fines in the impact strength test and compressive strength) and the brittleness of B-8 (half of the product of compressive strength and tensile strength) were calculated from the test results. Hourly slab productions were correlated with brittleness indexes. It was concluded that sawability of carbonate rocks can best be predicted from the brittleness of B-8.