[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Medications and dose calculation](https://durgical.com/en/nursing/areas/medication/) › Continuous infusions: concentration and rate per kilogram per minute # Continuous infusions: concentration and rate per kilogram per minute - Calculation For continuous infusions, work out the concentration of the mixture and convert the ordered dose (for example mcg/kg/min) into mL/h for the pump. Updated Nov 5, 2026 ## Key points - Educational, not a clinical order: fictional drugs and made-up numbers. - Concentration = amount of drug ÷ bag volume (convert mg to mcg if the order is in mcg). - mL/h = dose (mcg/kg/min) × weight (kg) × 60 ÷ concentration (mcg/mL). - mL/h = hourly dose (mg/h or units/h) ÷ concentration (mg/mL or units/mL). - Reverse: mcg/kg/min = mL/h × concentration ÷ 60 ÷ weight. - Always on a pump (a smart pump when available), with an independent double check. ## What it is Many critical-care drugs are ordered as a dose over time (mg/h, units/h) or per weight and time (mcg/kg/min). The pump, however, is set in mL/h. The bridge between the two is the concentration of the mixture: the amount of drug divided by the bag volume. With it you calculate the rate in mL/h or, the other way round, what dose the patient gets at the current rate. These are high-alert drugs: always on a pump with an independent double check. The examples use fictional drugs. ## Formulas - Concentration (mg/mL) = mg in the bag ÷ mL in the bag; × 1000 for mcg/mL. - Per weight and minute: mL/h = mcg/kg/min × kg × 60 ÷ mcg/mL. - Per hour: mL/h = (mg/h) ÷ (mg/mL), or (units/h) ÷ (units/mL). - Current dose: mcg/kg/min = (mL/h × mcg/mL) ÷ 60 ÷ kg. ## How to calculate it - Work out the bag's concentration and express it in the order's unit — mixing mg and mcg causes thousandfold errors. - Multiply the dose by the weight if the order is per kilogram — gives the patient's dose per minute or hour. - Multiply by 60 if the order is per minute — the pump works in hours. - Divide by the concentration — gives mL/h. - Do the reverse calculation to check — it must return the ordered dose. - Programme the pump and ask for a double check — catches programming errors. ## Worked examples (fictional drugs; educational, not a clinical order) | Data | Set-up | Answer | | --- | --- | --- | | Drug A 250 mg in 250 mL. Order: 5 mcg/kg/min. Weight: 80 kg. | Concentration 1 mg/mL = 1000 mcg/mL; 5 × 80 × 60 = 24 000 mcg/h; 24 000 ÷ 1000 | 24 mL/h | | Drug B 4 mg in 250 mL. Order: 0.1 mcg/kg/min. Weight: 70 kg. | 4000 mcg ÷ 250 mL = 16 mcg/mL; 0.1 × 70 × 60 = 420 mcg/h; 420 ÷ 16 | 26.25 ≈ 26.3 mL/h | | Drug C 400 mg in 250 mL running at 15 mL/h. Weight: 60 kg. What dose is the patient getting? | 1.6 mg/mL = 1600 mcg/mL; 15 × 1600 = 24 000 mcg/h; ÷ 60 = 400 mcg/min; ÷ 60 kg | 6.67 mcg/kg/min | | Drug D 25 mg in 250 mL. Order: 2 mg/h. | 25 ÷ 250 = 0.1 mg/mL; 2 ÷ 0.1 | 20 mL/h | | Drug E 25 000 units in 500 mL. Order: 1200 units/h. | 25 000 ÷ 500 = 50 units/mL; 1200 ÷ 50 | 24 mL/h | ## Common mistakes - Not converting mg to mcg when working out the concentration. - Forgetting to multiply by 60 when the order is per minute. - Using a weight different from the one recorded for the order. - Programming the pump in the wrong unit (mL/h instead of dose, or the reverse). ## Double-checking - Do the reverse calculation and compare with the order. - Ask another person to check the concentration, weight, rate and pump programming. - Check the bag label: concentration, date and time of preparation. ## Test yourself Think of the answer, then tap the question to see it. ## How is the concentration of an infusion mixture calculated? Divide the amount of drug by the bag volume (for example mg ÷ mL), and convert to mcg/mL if the order is in mcg. ## Why multiply by 60 when the order is in mcg/kg/min? Because the pump is set in mL per hour and an hour has 60 minutes. ## Educational example: 100 mg in 100 mL and an order of 5 mg/h. What rate in mL/h? Concentration 1 mg/mL; 5 ÷ 1 = 5 mL/h (made-up numbers, educational, not a clinical order). [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/nursing/continuous-infusions-concentration-and-rate-per-kilogram-per-minute/) ## Connections ## Related 3 - [IV flow rates: millilitres per hour and drops per minute](https://durgical.com/en/nursing/iv-flow-rates-millilitres-per-hour-and-drops-per-minute/) - [High-alert medications](https://durgical.com/en/nursing/high-alert-medications/) - [Weight-based doses (per kilogram) and paediatric safety](https://durgical.com/en/nursing/weight-based-doses-and-paediatric-safety/) [← All of nursing](https://durgical.com/en/nursing/) Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order. Sources: [Nursing Skills (Open RN), 5.17 Multi-Step Calculations](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/05%3A_Math_Calculations/5.17%3A_Multi-Step_Calculations) (Open RN, Chippewa Valley Technical College (LibreTexts), 2022); [Nursing Skills (Open RN), 5.15 IV Infusion by Pump](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/05%3A_Math_Calculations/5.15%3A_IV_Infusion_by_Pump) (Open RN, Chippewa Valley Technical College (LibreTexts), 2022); [Medication safety in high-risk situations](https://www.who.int/publications/i/item/medication-safety-in-high-risk-situations) (World Health Organization, 2019). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/nursing/continuous-infusions-concentration-and-rate-per-kilogram-per-minute/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/continuous-infusions-concentration-and-rate-per-kilogram-per-minute/