Suggested Rounding Guidelines for Parenteral Medication Dosages
Calculated
dosage amount
Rounding rule
Syringe
selection
Less than 1 mL
Work the problem to the thousandth place (3 places to the
right of the decimal point) and round to the hundredth
place.
Administer the
dose in a 1 mL
syringe
Example: Ordered is 30 mcg of medication. The
medication has a dosage strength of 90 mcg/mL. The nurse
solves the calculation to the thousandths place and arrives
at an answer of 0.333 mL.
The nurse cannot measure 0.333 mL in a syringe. The
answer to the calculation must be rounded so that it can be
drawn up and administered. Follow the rules of rounding
and round the answer to the hundredths place (0.33 mL).
The amount can be drawn up and administered in a 1 mL
syringe.
Greater than 1 mL
Work the problem to the hundredth place (2 places to the
right of the decimal point) and round to the tenths place.
Administer the
dose in a 3 mL
syringe
Example: Ordered 500 mg of medication. The medication
has a dosage strength of 300 mg/mL. The nurse solves the
calculation to the hundredths place (1.66 mL). The nurse
cannot measure 1.66 mL in a syringe. The answer must be
rounded to the tenths place (1.7 mL). This amount can be
drawn up and administered in a 3 mL syringe.
IV drip rates
Intravenous drip rates: When an answer is not a whole
number, work the problem to the tenths place (1 place to
the right of the decimal). Most IV pumps are set in mL/hr,
so the answer must be rounded to the nearest whole
number.
Example: 83.33 mL/hr. or 83 mL/per hour.
If you are regulating IV drips using a roller clamp (not
an IV pump) can you figure out how to make a partial
drop come down? NO, you cannot!!!
Castillo, S, & Werner-McCullough, M. (2021). Calculating drug dosages: A patient-safe approach to
nursing and math (2nd ed.). F.A. Davis Company. Pages 207, 298.