Given that 1 cup contains 8 ounces, 2/3 of a cup equals 5 1/3 ounces. As most measuring devices are not accurate to 1/3 of an ounce, it may be simpler to use an alternative unit of measurement.
Using standard household measuring methods, 2/3 of a cup is equivalent to 10 tablespoons plus 2 teaspoons. If using a 1.5-ounce jigger, use four measures to a tight tolerance.
If metric measurements are indicated on a liquid measuring cup, millilitres can be used instead. Given that 1 cup is roughly 236 millilitres, 2/3 of a cup equals roughly 157 millilitres.
