A liter of normal saline to infuse over 4 hours requires what rate in mL/hour?

• A. 250 mL/hour
• B. 125 mL/hour
• C. 500 mL/hour
• D. 200 mL/hour

Answer: (A)

Infusion rate is found by dividing the total volume to be infused by the time over which it will be given. Since 1 liter equals 1000 mL, delivering 1000 mL in 4 hours requires a rate of 1000 ÷ 4 = 250 mL per hour. This rate will deliver the entire volume exactly over four hours. For quick context, 125 mL/hour would take 8 hours, 500 mL/hour would take 2 hours, and 200 mL/hour would take 5 hours.