DIMENSIONAL ANALYSIS WORKSHEET
The Basic Equation:
1. Identify the unit of measure being calculated.
2. Insert the measure being calculated into the NUMERATOR of the FIRST fraction.
3. Identify the dosage strength available—place this value in the DENOMINATOR.
4. All ratios are entered so that the DENOMINATOR matches the unit of measurement of the next NUMERATOR.
EXAMPLE: The order is for 600 mg. The medication is available as 750 mg in 2.5 mL.
The measure being calculated is mL therefore:
mL = 2.5 mL X 600 mg = 10 = 2 mL
750 mg 1 5
Calculations that Require Metric Conversion:
A conversion factor must be added to provide match the denominator with the succeeding numerator.
1. Identify the unit of measure being calculated. Place this element in the numerator.
2. Identify the dosage strength available—place this value in the denominator.
3. Insert the appropriate ratio with the numerator matching the initial denominator.
4. Enter the dosage to be given.
EXAMPLE: The order is 275 mg. The medication is available as 0.5 g per 2 mL.
mL = 2 mL X 1 g X 275 mg = 1.1 mL
0.5 g 1000 mg 1
EXAMPLE: The order is 250 mcg. The label reads 0.25 mg. per tablet
Tablet = 1 tablet X 1 mg X 250 mcg = 1 tablet
0.25 mg 1000 mcg

DIMENSIONAL ANALYSIS WORKSHEET
IV Flow Rate Calculations
1. The gtt/min calculation requires the IV set calibration and the mL/hr ordered
2. Common flow rates are 10, 15, 20, or 60 gtt/mL.
3. Calculate for gtt/min. Enter gtt FIRST:
Example: 125 mL/hr using a set calibrated at 10 gtt/mL. gtt = 10 gtt X 125mL X 1 hr = 20.8 = 21 gtt/min min 1 mL 1 hr 60 min
Flow rates are rounded to the nearest whole number.
Dosage Calculations Based on Body Weight
1. Converting lb to kg
Divide lb by 2.2
41 lb 12 oz = 41.75 / 2.2 = 18.97 = 19 kg
2. Converting kg to lb
Multiply kg X 2.2 lb
23.3 kg = 23.3 X 2.2 = 51.26 = 51.3 lb