Weight-Based Infusion (mcg/kg/min) calculator
The weight-based infusion calculator converts a mcg/kg/min order — the form used for titrated drips such as norepinephrine, dopamine and dobutamine — into a pump rate in mL/hr. It needs the ordered dose, the patient weight, the milligrams of drug in the bag and the bag volume, because the concentration is what links dose to rate.
The formula
First the concentration: mcg/mL = drug (mg) x 1000 / bag volume (mL). Then the rate: mL/hr = dose (mcg/kg/min) x weight (kg) x 60 / concentration (mcg/mL). The factor of 60 converts minutes to hours.
A worked example
Norepinephrine 4 mg in 250 mL is 16000 mcg/mL / 250 = 16 mcg/mL. At 0.1 mcg/kg/min for an 80 kg patient: 0.1 x 80 x 60 / 16 = 30 mL/hr.
Concentration is the trap
The same drug is stocked at different concentrations across units and institutions, and a bag mixed to a different standard than the one you assumed produces a correct-looking rate that delivers the wrong dose. Read the milligrams and the volume off the actual bag every time, and re-check after any bag change.
What this does not do
This does not know the drug, its usual range, a maximum rate, or your unit protocol, and it does not titrate. High-alert infusions normally require an independent double check under your policy, and this calculator does not satisfy that requirement. Every result is a check on your arithmetic, not a clinical decision. Confirm the order, the concentration on the label and your own policy before administering anything.
Frequently asked questions
Which drips is this for?
Any order expressed in mcg/kg/min, which typically means vasoactive and inotropic infusions such as norepinephrine, dopamine or dobutamine.
Where do I get the drug amount and bag volume?
From the bag in front of you. Concentrations vary by institution, so an assumed standard is a real source of error.
Does this replace an independent double check?
No. Where your policy requires a second nurse for a high-alert infusion, that requirement stands.
My order is in mcg/min, not mcg/kg/min. Can I use this?
Not directly — this calculator expects a weight-based order. Use your unit reference for a non-weight-based rate.
By The Nursana team · Last updated · Canonical: https://nursana.aoneahsan.com/tools/weight-based-infusion
Nursana provides reference tools only and does not give medical, legal or tax advice.