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MedTestBankDosage Calculation for Nursing

mcg/kg/min to mL/hr Calculator (IV Drips)

Convert a weight-based critical care infusion in mcg/kg/min, or a dose in mcg/min, to a pump rate in mL/hr, and back.

mL/hr
kg
mg
mL

Enter the values: the answer and every step appear here as you type.

Formula

Concentration (mcg/mL) = drug (mg) × 1,000 ÷ bag volume (mL)

mL/hr = dose (mcg/kg/min) × weight (kg) × 60 ÷ concentration (mcg/mL)

mcg/kg/min = mL/hr × concentration ÷ 60 ÷ weight

How to calculate it step by step

  1. Find the concentration: convert the drug in the bag to mcg (mg × 1,000) and divide by the bag volume.
  2. Multiply the ordered dose by the weight in kg to get mcg/min (skip this step for an order in mcg/min).
  3. Multiply by 60 to get mcg/hr.
  4. Divide by the concentration to get mL/hr.

Worked examples

Example 1. Order: propofol 20 mcg/kg/min IV. The patient weighs 96 kg. Available: propofol 10 mg/mL (1,000 mg in 100 mL). At what rate in mL/hr will you set the pump?

  1. Concentration: 1,000 mg × 1,000 ÷ 100 mL = 10,000 mcg/mL.
  2. 20 mcg/kg/min × 96 kg = 1,920 mcg/min.
  3. 1,920 mcg/min × 60 = 115,200 mcg/hr.
  4. 115,200 ÷ 10,000 mcg/mL = 11.52 mL/hr, rounded to 11.5 mL/hr.

Answer: 11.5 mL/hr

Example 2. Order: norepinephrine 4 mcg/min IV. Available: norepinephrine 4 mg in 250 mL. At what rate in mL/hr will you set the pump?

  1. Concentration: 4 mg × 1,000 ÷ 250 mL = 16 mcg/mL.
  2. 4 mcg/min × 60 = 240 mcg/hr.
  3. 240 ÷ 16 mcg/mL = 15 mL/hr, rounded to 15 mL/hr.

Answer: 15 mL/hr

Rounding

Round the pump rate to the tenth of a mL/hr. Never round the concentration or the intermediate values.

Common mistakes

  • Forgetting to convert mg to mcg (× 1,000).
  • Forgetting the 60 minutes per hour.
  • Using the weight in pounds, or a weight-based formula for a drug ordered in mcg/min (norepinephrine and nitroglycerin are often ordered in mcg/min).

Nursing safety points

  • Vasoactive drips are high-alert medications: use the smart pump drug library and an independent double check.
  • Titrate only within the ordered range and toward the ordered goal (for example mean arterial pressure).
  • Use a central line when required and monitor the IV site closely for extravasation.

Frequently asked questions

How do you convert mcg/kg/min to mL/hr?

mL/hr = mcg/kg/min × kg × 60 ÷ concentration in mcg/mL. Dopamine 5 mcg/kg/min for 80 kg with 400 mg in 250 mL (1,600 mcg/mL): 5 × 80 × 60 ÷ 1,600 = 15 mL/hr.

How do you find the concentration in mcg/mL?

Multiply the mg in the bag by 1,000, then divide by the mL in the bag. 400 mg in 250 mL = 400,000 mcg ÷ 250 mL = 1,600 mcg/mL.

How do you calculate what dose is infusing?

mcg/kg/min = mL/hr × mcg/mL ÷ 60 ÷ kg. At 15 mL/hr of 1,600 mcg/mL for 80 kg: 15 × 1,600 ÷ 60 ÷ 80 = 5 mcg/kg/min.