Drug Infusion Rate from Dose Calculator

Enter Calculation

Dose (mcg/kg/min)

Patient Weight (kg)

Solution Concentration (mcg/mL)

Results

Infusion Pump Rate

13.12

mL per hour

Dose delivered	350 mcg/min
Hourly dose	21,000 mcg/hr

What This Calculator Does

This tool converts a weight-based drug dose into a continuous IV infusion pump rate expressed in millilitres per hour (mL/hr). It is widely used for vasoactive and titratable medications such as dopamine, dobutamine, norepinephrine and nitroglycerin, where the prescribed dose is given in micrograms per kilogram per minute (mcg/kg/min) but the infusion pump must be programmed in mL/hr. This is a general clinical calculation tool — always verify against your local protocols and a second clinician before administration.

How to Use It

Enter three values: the prescribed dose in mcg/kg/min, the patient weight in kilograms, and the concentration of the prepared solution in mcg/mL. The calculator returns the pump rate in mL/hr, plus the total dose delivered per minute and per hour for cross-checking.

The Formula Explained

The dose per minute is the dose multiplied by body weight (mcg/min). Multiplying by 60 converts this to an hourly dose (mcg/hr). Dividing by the solution concentration (mcg/mL) cancels the micrograms and leaves the volume per hour:

$$\text{Rate (mL/hr)} = \frac{\text{Dose (mcg/kg/min)} \times \text{Weight (kg)} \times 60}{\text{Concentration (mcg/mL)}}$$

If your concentration is labelled in mg/mL, multiply it by 1000 to convert to mcg/mL before entering it.

How dose, weight, time, and concentration combine to give the pump rate.

Components of a weight-based IV infusion: solution concentration, pump rate, and patient weight.

Worked Example

A 70 kg patient is prescribed dopamine at 5 mcg/kg/min. The bag contains 400 mg dopamine in 250 mL, giving a concentration of \(400{,}000 \text{ mcg} \div 250 \text{ mL} = 1600 \text{ mcg/mL}\). Dose per minute = \(5 \times 70 = 350 \text{ mcg/min}\). Hourly dose = \(350 \times 60 = 21{,}000 \text{ mcg/hr}\). Rate = \(21{,}000 \div 1600 =\) 13.13 mL/hr.

FAQ

What if my dose is in mcg/min (not weight-based)? Enter a weight of 1 kg and put the full dose in the dose field; the weight term then has no effect.

How do I find the concentration? Divide the total drug amount (in mcg) by the total volume of the bag (in mL).

Is this safe to use clinically? It is a calculation aid only. Always double-check with hospital protocols and an independent verification before infusing any medication.