Glossary
IV rate
An IV rate is the volume an infusion delivers per hour, found by dividing the total volume by the number of hours it runs.
An IV rate is the speed at which a volume is infused, usually written in milliliters per hour: total volume divided by hours. A liter over 8 hours is 1,000 ÷ 8 = 125 mL/hr, and the unit in the answer is the check that the division was set the right way round. Read the question for the time it gives — some state hours, some state minutes, and a rate in mL/hr needs hours before the division, so convert first. Two related quantities come up beside it. The drop rate converts the same volume into drops per minute using the set's drop factor, which is a separate calculation with a separate unit. And a weight-based order gives a per-kilogram rate that has to be multiplied by the patient's weight before the hourly figure exists. Hours must always be rounded as the pump is set, and the question states which way to round.
Taught in
Related terms
- drop factor — A drop factor is the number of drops an intravenous set delivers per milliliter, printed on the set's packaging, and it is what turns a volume into a drop count.
- unit rate — A unit rate is a rate reduced to one unit — dollars per item, kilometers per hour, milligrams per milliliter — which is what makes two offers comparable.
- proportion — A proportion is a statement that two ratios are equal, with one of the four values missing — and the missing value is what the calculation returns.
Source: The math guides in this course (ratio and proportion, measurement and conversion, dosage calculation): every definition and worked value above was written for this course, because arithmetic and unit conversion are not a publisher's prose, and each guide shows the method worked. Elsevier's own HESI A2 page, which names math among the areas the exam covers, is the exam-side source. (Elsevier HESI A2 page accessed 2026-10-23; definitions written 2026-10-27)