Nursing 102:
Comprehensive
Math Study Guide
for Dosage
Calculations
Updated 2026
, lOMoAR cPSD| 64664050
Study Guide:
Maths for Nursing
All nurses need to be competent in the calculation of medication dosages. You need to know how
to calculate required dosages accurately, including doses of tablets, doses of solutions, and
intravenous fluid rates and medications.
These drug calculations will require the application of some basic mathematics such as addition,
subtraction, multiplication, and division. You will also need to be able to:
• understand different measurements- such as weight and volume- and how to convert units
of measurements (for example, grams to milligrams)
• work with time calculations
• use formulas to calculate medication dosages
• calculate fluid rates in mL/hr and drop rates
• understand fractions and ratios
• convert between decimals and fractions and percentages
Units of measurement: weight
The gram is the basic unit of weight. The most common multiple of a gram is the kilogram,
which is 1000 times greater than the gram. The most common subdivision of a gram is the
milligram, which represents 1/1000 of a gram- or 0.001 g. The table below shows equivalencies
between units of weight:
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Comprehensive
Math Study Guide
for Dosage
Calculations
Updated 2026
, lOMoAR cPSD| 64664050
Study Guide:
Maths for Nursing
All nurses need to be competent in the calculation of medication dosages. You need to know how
to calculate required dosages accurately, including doses of tablets, doses of solutions, and
intravenous fluid rates and medications.
These drug calculations will require the application of some basic mathematics such as addition,
subtraction, multiplication, and division. You will also need to be able to:
• understand different measurements- such as weight and volume- and how to convert units
of measurements (for example, grams to milligrams)
• work with time calculations
• use formulas to calculate medication dosages
• calculate fluid rates in mL/hr and drop rates
• understand fractions and ratios
• convert between decimals and fractions and percentages
Units of measurement: weight
The gram is the basic unit of weight. The most common multiple of a gram is the kilogram,
which is 1000 times greater than the gram. The most common subdivision of a gram is the
milligram, which represents 1/1000 of a gram- or 0.001 g. The table below shows equivalencies
between units of weight:
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