Dosage Calculations & IV Infusion Rates: Metric System & Measurement Equivalents

Metric System

A system of measurement that includes units such as milliliters (mL), milligrams (mg), and grams (g).

1000 milliliters (mL)

Equivalent to 1 liter.

1000 milligrams (mg)

Equivalent to 1 gram.

1000 micrograms (mcg)

1 milligram (mg)

1 liter

1000 milliliters (mL)

1 gram

1000 milligrams (mg)

1 milligram

1/1000 0.001 of a gram

1 kilogram (kg)

Equivalent to 2.2 pounds (lb).

1 ounce (oz)

30 milliliters (mL)

1 Tablespoon (T or tbs)

15 milliliters (mL)

1 teaspoon (t or tsp)

5 milliliters (mL)

1 inch (in)

Unit of length equal to 2.54 centimeters.

30 milliliters (mL)

1 ounce (oz)

15 milliliters (mL)

1 tablespoon (T)

5 milliliters (mL)

1 teaspoon (tsp)

2.54 centimeters (cm)

Equivalent to 1 inch.

Rounding Rules

Guidelines for rounding measurements in dosage calculations.

IV drip rates

The rate at which intravenous fluids are administered.

Trailing Zero

A zero placed after a whole number, which should never be used (e.g., 2.0 mg is never used).

Leading Zero

A zero placed before a dose less than 1 (e.g., 0.125 mg, 0.5 mL, 0.3 g).

Calculating gtt/minute based on hours

Formula: mL/hr x gtt/mL = gtt/minute.

Calculating mL/hr for infusion pump

Formula: total number of milliliters ordered = mL/hr / number of hours to infuse.

Calculating rate for infusions less than 60 minutes

Formula: volume to be infused x 60 = mL/hr / time of the infusion.

Convert Celsius to Fahrenheit formula

F= 1.8 (*C) + 32

Convert Fahrenheit to Celsius

C= F-32/1.8

Dosage calculations

Dose/have(times)volume=x