Nursing specialty hub
ICU / Critical Care nursing calculators & guides
Start with the ICU task in front of you: program or verify an infusion, calculate a pump rate, check a final concentration, or work through renal and metabolic arithmetic. Lower-priority gravity drip checks remain available further down the page.
Start with the task
What do you need to work out right now?
Choose the statement that looks most like the order, infusion or result in front of you.
I need to set or verify a mcg/kg/min infusion
Use the prescribed weight-based dose, patient weight and verified infusion concentration.
I have a volume and time. What mL/hr do I set?
Calculate the pump rate directly from the prescribed volume and infusion time.
I need to check the final IV concentration
Use verified reconstitution, transfer and final-volume values to check the bag or syringe concentration.
I need an anion gap
Enter the reported electrolytes to calculate the gap without MedMaths assigning a diagnosis.
ICU calculator toolkit
Calculators grouped by ICU workflow
The most immediate pump and infusion calculations come first. Renal and metabolic tools follow, with gravity-line checks kept available as a secondary workflow.
Critical infusions
Program or check an infusion
Start here for weight-based infusions, pump-rate arithmetic, final concentration checks and infusion duration.
mcg/kg/min Infusion Rate Calculator
Use this when
Use when programming or verifying a weight-based infusion of a vasoactive, sedative, or inotropic agent in mcg/kg/min.
Open calculatorIV Infusion Rate Calculator
Use this when
Use when the order says a volume over a time and you need the mL/hr pump rate. No drop factor is required.
Open calculatorIV Infusion Time Calculator
Use this when
Use when you know the volume to infuse and mL/hr rate and need to know how long it will take or when it will finish.
Open calculatorFinal IV Bag Concentration Calculator
Use this when
Use after product- or pharmacy-specific reconstitution and transfer values are already verified.
Open calculatorRenal + metabolic
Check renal function or metabolic arithmetic
Use the equation named by the clinical reference and keep the calculated value separate from diagnosis or treatment decisions.
Anion Gap Calculator
Use this when
Use when you need the potassium-free anion-gap arithmetic, with optional albumin adjustment, for comparison with the reporting laboratory reference interval.
Open calculatorSerum Osmolality Calculator
Use this when
Use when you need calculated serum osmolality or, with a measured value, the numeric measured-minus-calculated osmol gap.
Open calculatorCorrected Sodium Calculator
Use this when
Use when a current source asks for a Katz or Hillier hyperglycaemia-adjusted sodium estimate from measured sodium and glucose.
Open calculatorCreatinine Clearance Calculator
Use this when
Specific-method calculator for sources that explicitly require Cockcroft-Gault CrCl and a defined weight method.
Open calculatoreGFR Calculator (CKD-EPI 2021)
Use this when
Modern adult renal-function pathway for eGFR and medication-related workflows when the governing source uses CKD-EPI.
Open calculatorGravity + line checks
Check a gravity infusion when you need it
These remain available for manual drip-rate calculations and checking an observed gravity line, but they sit below the pump-based ICU workflows.
IV Drip Rate Calculator
Use this when
Use when the giving-set drop factor is known and the order provides either mL/hr or total volume and time.
Open calculatorObserved gtt/min to mL/hr Calculator
Use this when
Use only when the gravity drip is already running and you counted whole drops over one full minute, or made a quick 15-second whole-drop count, with the exact giving-set drop factor.
Open calculatorBrowse by calculation type
Calculation topics used in ICU / Critical Care
These topic hubs group the same calculators by calculation type. Use them when you want to move from this specialty view into the wider MedMaths calculation pathway.
Calculation topic
IV Fluids & Infusions
Choose by the answer you need: pump rate in mL/hr, gravity drops/min, infusion duration, or a check of an existing drip.
Open topic hubCalculation topic
Dilutions & Concentration
Choose between C1V1=C2V2 dilution arithmetic and a verified-input final IV bag concentration check. Use mg to mL for vial withdrawal volume.
Open topic hubCalculation topic
Renal Dosing Support
Start with modern CKD-EPI 2021 eGFR or use Cockcroft-Gault CrCl when a current source specifically requires it.
Open topic hubCalculation topic
Lab Calculators & Corrections
Laboratory calculation tools for corrected calcium, corrected sodium, anion gap, serum osmolality and osmol gap.
Open topic hubLearning
Related MedMaths guides
mcg/kg/min Infusions Explained: Dose Rate and Pump Rate
Learn how mcg/kg/min connects dosing weight, time and infusion concentration to mL/hr, including forward and reverse calculations, unit checks and high-risk infusion safety boundaries.
Medication Dose Rate vs Pump Rate Explained
Understand dose rate versus pump rate, calculate mg/hr from concentration and mL/hr, convert mg/hr and mg/min, and recalculate mL/hr after an authorised medication-rate or concentration change.
Calculated Serum Osmolality and Osmol Gap Explained
Understand directly measured vs calculated serum osmolality, effective osmolality/tonicity, what the osmol gap represents, why formulas and ethanol coefficients change the result, and why the gap must be interpreted as a clue rather than a diagnosis.
eGFR vs CrCl: which renal function estimate should you use?
Understand how CKD-EPI eGFR and Cockcroft-Gault CrCl differ, why their values may not match, and how to follow the estimate and units required by the current source.
Use the calculator guidance for each clinical situation
Specialty grouping is designed to help you find tools faster. Always follow the guidance on the individual calculator page, medication references, local policy, and clinical review requirements.