1 Teaspoon [US] = 0.166666667 (1/6) Ounce [Fluid, US]
1 Teaspoon [UK] = 0.208333333 Ounce [UK]
Teaspoon is a volume unit and frequently used in cooking recipes and prescriptions. 1 US tsp is about 5 mL and 1/6 of a fluid ounce. The abbreviations are "tsp", "ts". The abbreviations are always in small letters since when in used in capital letters, usually mistaken with larger volume unit, tablespoon.
Fluid ounce is an imperial and US Customary volume unit. The abbreviation is "fl oz".