Infusion rate converter (mcg/kg/min to mL/hr)

To convert mcg/kg/min into mL/hr, multiply the dose by weight in kilograms and by 60, then divide by the concentration of the bag in micrograms per millilitre. The two traps are forgetting the factor of 60 for minutes to hours, and mixing milligrams in the bag with micrograms in the order.

When to use the mcg/kg/min to ml/hr calculator

Use for any weight-based continuous infusion, which in practice means vasopressors, inotropes and sedatives in critical care. These are the orders where a rate error has immediate consequences.

The mcg/kg/min to ml/hr formula

Rate in mL/hr = (dose in mcg/kg/min × weight in kg × 60) ÷ concentration in mcg/mL. Concentration in mcg/mL = (mg in the bag × 1000) ÷ bag volume in mL.

Worked example

Noradrenaline 4 mg in 50 mL at 0.1 mcg/kg/min for a 70 kg patient. Concentration = (4 × 1000) ÷ 50 = 80 mcg/mL. Rate = (0.1 × 70 × 60) ÷ 80 = 420 ÷ 80 = 5.25 mL/hr.

The mistake that costs marks

Three unit conversions hide in one calculation: milligrams to micrograms in the bag, minutes to hours in the rate, and the per-kilogram step. Dropping the ×60 gives a rate 60 times too low, and forgetting the ×1000 gives one 1000 times too high. Write the units beside every number and cancel them.

Study aid, not a clinical tool

This calculator exists so you can learn the method and check your working for an examination. It is not medical advice and not clinical decision support, and it must not be used to make a decision about a real patient. Verify any result against your local formulary, the product literature and a qualified pharmacist. Our medical disclaimer sets out the full position.

Calculators you will usually need alongside this

Most questions that reach for one of these reach for another a step later, so these are the three that most often pair with it.

• IV drip rate calculator — IV drip rate
• Loading dose calculator — Loading dose
• mg/kg dose calculator — Weight-based dose

Keep going

Calculations are only half of what examinations test. The other half is knowing why a drug does what it does, which is what decides whether a number you calculated is even the right number to be calculating. Start with Best pharmacy calculators. The drug class pages cover the mechanism behind the number, or browse the rest of the free calculators and try the practice questions.