Rebaudioside A (CAS NO.:58543-16-1, Chemical formula: C44H70O23, sometimes shortened to "Reb A") is a steviol glycoside from the leaves of Stevia rebaudiana that is 240 times sweeter than sugar. Rebaudioside A is the sweetest and most stable steviol glycoside, and is less bitter than stevioside. Stevia leaves contain 9.1% stevioside and 3.8% rebaudioside A.