The mcg/kg/min to mL/hr calculator converts a weight-based, time-based drug infusion dose into the pump rate a nurse programs in millilitres per hour. This calculation is used daily in intensive care, emergency, and perioperative nursing for vasopressors (dopamine, norepinephrine), inotropes (dobutamine, milrinone), and sedation infusions. Enter the ordered dose, patient weight, and drug concentration to get the precise pump rate.
To convert mcg/kg/min to mL/hr, use (dose × weight × 60) ÷ concentration in mcg/mL. For dopamine 5 mcg/kg/min in a 70 kg patient with 400 mg in 250 mL (1,600 mcg/mL): (5 × 70 × 60) ÷ 1,600 = 13.1 mL/hr. Convert the bag from mg to mcg first — that unit step is where most errors happen.
| Drug | Typical Dose Range | Effect |
|---|---|---|
| Dopamine (low) | 1–5 mcg/kg/min | Renal/mesenteric vasodilation |
| Dopamine (mid) | 5–10 mcg/kg/min | Inotropic / cardiac output |
| Dopamine (high) | 10–20 mcg/kg/min | Vasopressor |
| Dobutamine | 2–20 mcg/kg/min | Inotrope — heart failure |
| Nitroprusside | 0.1–5 mcg/kg/min | Vasodilator — hypertensive crisis |
| Milrinone | 0.375–0.75 mcg/kg/min | Inodilator |
Pump rates for a 70 kg patient using commonly stocked bag concentrations. Each is worked with mL/hr = (dose × weight × 60) ÷ concentration in mcg/mL. Always check the concentration on the bag in front of you — it varies by unit and by pharmacy.
| Drug & bag | Concentration | Dose | Rate (70 kg) |
|---|---|---|---|
| Dopamine 400 mg / 250 mL | 1,600 mcg/mL | 5 mcg/kg/min | 13.1 mL/hr |
| Dopamine 400 mg / 250 mL | 1,600 mcg/mL | 10 mcg/kg/min | 26.3 mL/hr |
| Dobutamine 250 mg / 250 mL | 1,000 mcg/mL | 5 mcg/kg/min | 21.0 mL/hr |
| Dobutamine 250 mg / 250 mL | 1,000 mcg/mL | 10 mcg/kg/min | 42.0 mL/hr |
| Nitroprusside 50 mg / 250 mL | 200 mcg/mL | 0.5 mcg/kg/min | 10.5 mL/hr |
| Milrinone 20 mg / 100 mL | 200 mcg/mL | 0.375 mcg/kg/min | 7.9 mL/hr |
| Milrinone 20 mg / 100 mL | 200 mcg/mL | 0.5 mcg/kg/min | 10.5 mL/hr |
Take dopamine 400 mg in 250 mL, ordered at 5 mcg/kg/min for a 70 kg patient.
Step 1 — find the concentration. 400 mg is 400,000 mcg. Divide by the bag volume: 400,000 ÷ 250 = 1,600 mcg/mL.
Step 2 — find the dose per minute. 5 mcg/kg/min × 70 kg = 350 mcg/min.
Step 3 — convert to per hour. 350 × 60 = 21,000 mcg/hr.
Step 4 — divide by the concentration. 21,000 ÷ 1,600 = 13.1 mL/hr.
The step that trips people up is the units — the dose is in micrograms and the bag is usually labelled in milligrams, so converting first is what keeps the arithmetic honest. And because these are potent drugs with narrow margins, the result should be checked by a second nurse before it goes near the pump.
Common drugs dosed in mcg/kg/min include dopamine, dobutamine, norepinephrine (noradrenaline), milrinone, nitroprusside, and some sedation agents. These are almost exclusively used in ICU, ED, and perioperative settings due to their potency and narrow therapeutic windows.
The formula is: mL/hr = (Dose in mcg/kg/min × Weight in kg × 60) ÷ Concentration in mcg/mL. For example, dopamine 5 mcg/kg/min for a 70 kg patient with 400mg in 250mL (1600 mcg/mL): mL/hr = (5 × 70 × 60) ÷ 1600 = 13.1 mL/hr.
Multiply the dose (mcg/kg/min) by the patient's weight in kg, multiply by 60 to get an hourly figure, then divide by the bag concentration in mcg/mL. Convert the bag from mg to mcg first — that unit step is where most errors happen.
With the common bag of dopamine 400 mg in 250 mL (1,600 mcg/mL), the rate is 13.1 mL/hr. Working: 5 mcg/kg/min × 70 kg = 350 mcg/min, × 60 = 21,000 mcg/hr, ÷ 1,600 mcg/mL = 13.1 mL/hr.