Nursing Math Medication and IV Formulas

Dose Formula: Solids

\frac{O}{A}

O = Dose ordered
A = Dose available

Dose Formula: PO Liquids, Injectables, Dose → mL:

\frac{O \times V}{A}

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

Hours → mL/hr:

\frac{V}{H}

V = Volume
H = Hours

Minutes → mL/hr:

\frac{V \times 60 min}{M}

V = Volume
M = Minutes

mcg/min → mL/hr:

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

\frac{D \times 60 min}{1000 mcg}

D = Dose (mcg)

Then use the dosage formula to calculate rate.

\frac{O \times 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).

\frac{D \times W \times 60 min}{1000 mcg}

D = Dose (mcg)
W = Weight (kg)

Then use the dosage formula to calculate rate.

\frac{O \times V}{A}

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

Time ← mL/hr

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

\frac{V}{R}

V = Volume
R = Rate

Hours ← gtt/min:

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

\frac{V \times C}{(G \times 60 min)}

V = Volume
C = IV tubing calibration
G = gtt/min

1 × Dose, dose/hr ← mL/hr:

\frac{R \times 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).

\frac{R \times A}{V}

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

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

\frac{D \times 1000 mg}{60 min}

D = Dose (mg)

mcg/kg/min ← mL/hr:

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

\frac{R \times 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).

\frac{D \times 1000 mg}{(60 min \times W)}

D = Dose (mg)
W = Weight in kilograms (kg)