Medication Calculation
Important Conversion Factors
Common Abbreviations
To succeed on the Medication Calculation
Proficiency Quiz it is recommended that
you memorize the conversions in this list.
This list is not meant for memorization. It is simply to provide a
reference to help clarify common abbreviations used in
medication calculation questions.
1000 mcg = 1 mg
PO = By mouth
1000 mg = 1 g
IV = Intravenous
2.2 lb = 1 kg
IVPB = IV Piggy Back (or Secondary Infusion)
1000 ml = 1 L
IM = Intramuscular
5 ml = 1 tsp
subcut = Subcutaneous
15 ml = 1 Tbsp
Q4 = Every four hours
3 tsp = 1 Tbsp
Q6 = Every six hours
30 ml = 1 oz
Q12 = Every twelve hours
240 ml = 1 cup
qday = Every day
8 oz = 1 cup
bid = Twice a day
tid = Three times a day
qid = Four times a day
PRN = As Needed
mEq = milliequivalents
gtt/ml=Drop Factor (gtt comes from “gutta” which is Latin for
drop)
NS = Normal Saline Solution
LR = Lactated Ringer’s Solution
D5W= 5% Dextrose in Water Solution
Medication Calculation Tip Sheet
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Dimensional analysis is the format taught to solve problems. Refer to your Ogden/Fluharty text,
Chapter 12, page 171 for review of dimensional analysis.
o If another format for solving works better for you, stick to what works best.
Identify what the question is asking you for before setting up your equation. If it helps consider
underlining or circling the unit of measure you are being asked to solve for to keep this clear
throughout problem solving.
o For example: Patient X is prescribed 10mg Senna PO qday as needed. Senna is available in
5mg tablets. How many tablets should patient X take?
All rounding should occur at the end of a problem EXCEPT weight-based problems. Convert pounds
to kilograms before setting up your equation. Round kilograms to the tenths place prior to inserting
into your equation.
o For example: Patient Y weighs 80 lb. Patient Y is prescribed 2mg/kg of ibuprofen PO q6h.
How many milligrams are needed to give the correct dose?
1kg * 80lb = 36.3636 kg = 36.4 kg
2mg * 36.4kg = 72.8 mg
2.2lb
**Note: If you do not round kg beforehand you get a different answer!**
Always round to the tenths place EXCEPT for IV drips. IV drips are the only instance you should
round to a whole number.
Rounding rules:
o Identify your goal place value. (Tenths unless it is an IV drip.)
o Identify number to the right of your goal place value.
o If number to the right of the goal place value is less than 5 then the place value number will
remain the same (0, 1, 2, 3, 4).
 Solve to a whole number 1.2=1
 Solve to the tenths place 0.43=0.4
If number to the right of the goal place value is equal to or greater than 5 then the place value
number will increase by one (5, 6, 7, 8, 9).
o Solve to a whole number 0.6=1
o Solve to the tenths place 1.582=1.6
Gravity infusion questions will require a drop factor. The drop factor can be found on the packaging
of the IV tubing being used.
Always recheck your math! You will have plenty of time to solve each problem and review over your
math. Don’t let a silly mistake cost you a passing grade.
Medication calculation is a skill and takes practice. Continue to do practice problems and review
your resources.
Seek out help sooner rather than later! If you are having trouble setting up problems or finding the
correct answer please utilize the resources available to you.