How many milliliters are in 1 fluid ounce (oz)?

• A. 30 ml
• B. 28 ml
• C. 25 ml
• D. 20 ml

Answer: (B)

Converting fluid ounces to milliliters requires knowing which fluid ounce is being used. The imperial (UK) fluid ounce is about 28.41 mL, which rounds to 28 mL. The US fluid ounce is about 29.57 mL, which rounds to 30 mL. In many veterinary practice contexts, the imperial value is assumed unless stated otherwise, so 1 fluid ounce is approximately 28 mL, making that the best match among the options. The 30 mL choice would fit US units, while 25 or 20 mL are farther from either standard value.