A 70 kg adult following the 30-40 mL/kg/day guideline would require approximately how many milliliters per day?

• A. 1050-1400 mL
• B. 2100-2800 mL
• C. 3500-4200 mL
• D. 4900-5600 mL

Answer: (B)

Maintenance fluid needs in adults are commonly estimated at 30–40 mL per kilogram per day. For a person weighing 70 kg, that translates to 70 × 30 = 2100 mL and 70 × 40 = 2800 mL, so about 2100–2800 mL per day. This is the approximate daily fluid requirement for maintenance. The other ranges imply lower or higher maintenance per kg (for example, 15–20 mL/kg/day would be about 1050–1400 mL, while 50–60 or 70–80 mL/kg/day would be around 3500–4200 or 4900–5600 mL), which fall outside the typical maintenance range for a standard adult.