St. Anthony College of Nursing
N307
Essential Math Conversions and Formulas
Unit
Term
Abbreviation
Weight gram
milligram
microgram
kilogram
g
mg
mcg
kg
1 g = 1000 mg
1 mg = 1000 mcg = 0.001 g
1 mcg = 0.001 mg =
0.000001 g
1 kg = 1000 g
Volume liter
milliliter
L
mL
1 L = 1000 mL
1 mL = 0.001 L
1 tsp = 5 ml
1 tbsp = 15 ml
1 oz = 30 ml
1 cup/8 oz = 240 ml
1 gr = 60 mg
1 kg = 2.2 pounds
FORMULAS
IV flow rate
Calculate ml/hr
Total volume in ml / total time in hours
Dosage Calculation
D X V = A D = desired/ordered dose
H
H = have/available dose
V = volume or quantity
A = dose to administer
Drops per minute
Volume to be infused X drop factor (gtt/ml) = drops/minute
Time in Minutes
Advanced IV calculations
R = D X 60
C
R = Rate ml/hr
D = Dose (ordered by physician/NP) mg or mcg/min, mg or
mcg/kg/min, mg or mcg/hour)
60 = constant if going from minutes to hours (NOT use if
ordered in hours and rate is ml/hour)
C = Concentration total amount med/total volume
(Ex. mg or mcg/ml)