How is the infusion concentration found?

Concentration in mg/mL is the drug mass in the bag divided by the bag volume. For example 400 mg in a 250 mL bag is 1.6 mg/mL, or 1600 mcg/mL. The pump rate calculation depends on this value.

How is a weight-based pump rate calculated?

First convert the target to mg/min: target mcg/kg/min times weight in kg, divided by 1000. Then the rate in mL/hr equals that mg/min times 60, divided by the concentration in mg/mL. The tool shows each step.

When do I use mg/hr instead of mcg/kg/min?

Use mg/hr for drugs ordered as a fixed hourly dose, such as some sedatives or heparin. Use mcg/kg/min for weight-titrated vasoactive drugs like noradrenaline or dopamine. The tool supports both modes.

Why does concentration matter so much?

The same target dose needs very different pump rates depending on how concentrated the bag is. Double-concentrated bags halve the mL/hr. Always confirm the bag concentration matches what the pump is programmed to expect to avoid serious dosing errors.

Is this safe to use alone for high-alert drugs?

No. Vasoactive and sedative infusions are high-alert. Verify every calculation against the protocol, the pump's settings, and a second clinician. This tool is an educational double-check and runs entirely in your browser.

What is the Infusion Concentration & Rate Calculator?

From the drug mass in an IV bag and the bag volume, compute the concentration and the pump rate in mL/hr needed to deliver a target dose in mcg/kg/min or mg/hr. For ICU and theatre. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Infusion Concentration & Rate Calculator

Name: Infusion Concentration & Rate Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Continuous infusions of vasoactive and sedative drugs are ordered as a dose (mcg/kg/min or mg/hr) but delivered as a volumetric pump rate (mL/hr). This tool bridges the two by first finding the bag concentration, then the rate that delivers the target dose — useful as a bedside double-check and for teaching the underlying arithmetic.

How it works

The bag concentration is mass divided by volume:

concentration (mg/mL) = drug_mg / bag_volume_mL

For a weight-based order (e.g. noradrenaline, dopamine, dobutamine):

dose (mg/min) = target_mcg_kg_min × weight_kg / 1000
rate (mL/hr)  = dose_mg_min × 60 / concentration_mg_mL

For a fixed hourly dose (e.g. heparin, some sedatives):

rate (mL/hr) = target_mg_hr / concentration_mg_mL

Worked example — weight-based

A bag holds 400 mg of drug in 250 mL, a concentration of 1.6 mg/mL (or 1,600 mcg/mL). To deliver 5 mcg/kg/min to a 70 kg patient:

Convert dose to mg/min: 5 × 70 ÷ 1,000 = 0.35 mg/min
Convert to mg/hr: 0.35 × 60 = 21 mg/hr
Divide by concentration: 21 ÷ 1.6 = 13.1 mL/hr

Set the pump to 13.1 mL/hr to deliver the target dose.

Worked example — fixed mg/hr

A sedative is ordered at 10 mg/hr from a bag of 500 mg in 100 mL (concentration = 5 mg/mL):

rate = 10 mg/hr ÷ 5 mg/mL = 2 mL/hr

This is why highly concentrated bags run at very low pump rates and require particular care — a small programming error moves the rate by a clinically significant fraction.

Why concentration matters so much

The same target dose in mcg/kg/min can require vastly different pump rates depending on bag concentration. For example, a double-concentrated bag (same drug mass in half the volume) halves the mL/hr needed for the same dose. Errors arise when:

A replacement bag is mixed at a different concentration to the running bag.
The pump’s drug library profile is set to a different concentration to the bag actually hanging.
The patient weight entered in the pump differs from the weight used here.

Always confirm the concentration matches what the infusion pump is programmed to expect before connecting a new bag or adjusting the rate.

Safety notes

Vasoactive infusions (noradrenaline, adrenaline, vasopressin, dopamine) and sedatives (propofol, midazolam, ketamine) are high-alert medications. This tool is an educational double-check and teaching aid. Every clinical calculation must be independently verified against the unit protocol, the drug monograph, and by a second qualified clinician or pharmacist before administration. Calculations run entirely in your browser and nothing is stored or transmitted.