The effects of chemical composition and cooling rate on the delta ferrite formation in austenitic stainless steels have been investigated. Ferrite fractions measured by a magnetic method were in the range of 0 to 12% and were compared with those calculated by empirical formulas available in the literature. The delta ferrite formation (amount and distribution) was strongly affected by the steel chemical composition, but less affected by the cooling rate. Among several formulas used to calculate the amount of delta ferrite, the best agreement was obtained with those proposed independently by Schneider and Schoefer, the latter being recommended in the ASTM 800 standard.