Application to Basic Mathematics to Medication Dosage

Conversion of the SI, British and Household systems of the selected problems:

Household to Household Conversion

  1. Convert 6 teaspoons to table spoons.

1 Solution:

Step– 1: Equivalent?

As we know that 1 tablespoon = 3 teaspoon              conversion factor = 3.

Step-2: Multiply or divide?

Conversion is to larger units. Divide by the conversion factor.

6 teaspoon = 6 / 3 = 2

Hence 6 teaspoon = 2 tablespoon

For practice

  1. 7 T = ___ t
  2. 12t = ___ T
  3. ____T = 23 t

SI and Household Conversion

  1. ____ mL = 3t


Step– 1: Equivalent?

As we know that 1 teaspoon = 5 mL              conversion factor = 5.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

3 teaspoon = 3 X 5 = 15 mL

Hence 3 teaspoon = 15 mL

For practice:

Calculate the equivalent measures.

  1. _____ mL = 4 t
  2. _____ mL = 3T
  3. _____ mL     = 7t
  4. 30 mL = _____ Tablespoon
  5. 20 mL = _____ teaspoons

SI and British Conversion

  1. ____ mL = 3 ounce


Step– 1: Equivalent?

As we know that 1 ounce = 30 mL                 Conversion factor = 30.

Step-2: Multiply or divide?

Conversion is to smaller units. Multiply by the conversion factor.

3 ounces = 3 X 30 = 90 mL

Hence 3 ounces = 90 mL

For practice:

Convert the following:

  1. 2 ounces = _____ mL
  2. 120 mL  = _____ ounces
  3. 2 T = _______ ounces


Other Drug Measures (Units and milliequivalents) 

Quantities of drugs may be included in units (U) or milliequivalents (mEq). Conversions for either milliequivalents or units are un-necessary. Drugs in these measurements are prescribed, prepared, and administered all in the same system.

Units and milliequivalents

A Unit (not a weight measurement) is an amount of a drug which produces a certain effect. The meaning of units varies with the particular drug being measured, since the amounts and the related effects of various drugs differ. Insulin is a familiar drug administered in Units.

A milliequivalent is a measurement of the weight of a drug contained in a certain volume of solution.  

The quantities of the Units and milliequivalents are written Arabic numerals followed by the appropriate symbol, U or mEq.

SYMBOLIC NOTATION                                       MEANING

10, 25, or 10,000 U etc                                                           10, 25 or 10,000 units

5,,10, or 25 mEq etc                                                               25 milli equivalents etc


  1. Generic and Brand Name of the Drug

Most labels, however, identify a drug by two names, one is the official (generic) name of the drug, the other name is the brand or trade name which is identified by ®, the registration symbol.

For example:                                                        

Generic Brand Name


Ibuprofen Brufen


diclofenace sodium Tab: Dicloran, Dyclo, Voltral,

Cap: Philogen etc.


cephradine Velocef,


co-trimaxazole Septran, Penetrin, Biotran, Nicotrim etc.


Note:  Name of drug to be given (trade/brand name is started with capital letter & generic name is written with small letters)

  1. Dosage strength (weight of the drug)

The dosage strength or weight of the drug is written on the label with a unit of measure such as gram, milligram, Units, mEq, for example 250 mg, 2g, 250 U, 1000 U, 20 mEq etc.


Combination drugs are preparations which contain a mixture of several drugs together. Often the dosage strength is not listed for combination drug. They are ordered by tablet, capsule, or by milliliters, and not by dosage strength.

  1. Form of the drug

The drug may be in solid (tablet, capsule, etc) or liquid form (syrup, suspension, etc.). A tablet or capsule contains a certain weight of a drug. A volume of solution (usually stated in mL or cc) contains a certain weight of a drug.

  1. Supply Dosage (On Hand Dosage)

The supply dosage or On-Hand Dosage is the dosage strength (weight) together with the form of drug.

Dosage strength form Supply dosage On-Hand Dosage


Solid: 50 mg In        1 tablet 50 mg/tablet
Solid: 50 mg In         1cc 50 mg/cc
Solid: 200 mg In       1 capsule 200 mg/capsule
Liquid: 200mcg In        5 mL 200 mcg/5 mL
Liquid: 1000 U In        1 mL 1000 U/1 mL

 Note: The dosage ordered by the Physician may be expressed in terms of weight only. The order may not state the number of milliliters (or cc) necessary to deliver that dosage.

  1. Total Container Volume

The total number of milliliters (mL) or cubic centimeter (cc) in the container (bottle) is listed on the label. Today, many tablets or capsules are packed in unit dosage; that is, a single tablet or capsule in a blister pack. A container may hold multiple doses; while the total number of tablets or capsules is identified.

  1. Direction for mixing or Reconstituting powdered Drugs

Certain drugs that are supplied in powder form must be dissolved in a liquid before they can be administered. The directions for preparing solutions from powdered drugs may be printed on the drug label or may be included in the drug literature or inserters.

  1. Expiration Date and Additional Information

The expiration date is the last date on which the drug be used. Expiration may be abbreviated as EXP. Warnings regarding storage and the use of the drug are examples of other information which may be included on the drug label.