Nursing Math Medication and IV Formulas

Dose Formula: Solids

O A
  • O = Dose ordered
  • A = Dose available

Dose Formula: PO Liquids, Injectables, Dose → mL

O × V A
  • O = Dose ordered
  • V = Volume of dose available
  • A = Dose available

Calculate IV rate as mL/hr using hours:

V H
  • V = Volume
  • H = Hours

Calculate IV rate as mL/hr using minutes:

V × 60 min M
  • V = Volume
  • M = Minutes

mcg/min → mL/hr

First, convert micrograms per minute (mcg/min) to milligrams per hour (mg/hr).

D × 60 min 1000 mcg
  • D = Dose (mcg)

Then use the dosage formula to calculate rate.

O × V A
  • O = Dose ordered
  • V = Volume of dose available
  • A = Dose available

mcg/kg/min → mL/hr

First, convert micrograms per kilograms per minute (mcg/kg/min) to milligrams per hour (mg/hr).

D × W × 60 min 1000 mcg
  • D = Dose (mcg)
  • W = Weight (kg)

Then use the dosage formula to calculate rate.

O × V A
  • O = Dose ordered
  • V = Volume of dose available
  • A = Dose available

Calculate Time in Hours with IV pump

Use the basic time formula with an IV pump to calculate hours.

V R
  • V = Volume
  • R = Rate

Calculate Time in Hours without IV pump

Drops/minute (gtt/min) must be converted into hours when using calibrated tubing without a pump.

V × C ( G × 60 min )
  • V = Volume
  • C = IV tubing calibration
  • G = gtt/min

1 × Dose, dose/hr ← mL/hr

R × A V
  • R = Rate
  • A = Dose available
  • V = Volume of dose available

mcg/min ← mL/hr

First, determine the dosage given milligrams/hour (mg/hr).

R × A V
  • R = Rate
  • A = Dose available
  • V = Volume of dose available

Next, convert dosage from mg/hr to microgram/minute (mcg/min).

D × 1000 mg 60 min
  • D = Dose (mg)

mcg/kg/min ← mL

First, determine the dosage given milligrams/hour (mg/hr).

R × A V
  • R = Rate
  • A = Dose available
  • V = Volume of dose available

Next, convert dosage from mg/hr to microgram/kilogram/minute (mcg/kg/min).

D × 1000 mg ( 60 min × W )
  • D = Dose (mg)
  • W = Weight in kilograms (kg)