Insulin Drip Calculator (units/hr to mL/hr)
Calculate the pump rate for an IV regular insulin infusion from units/hr or units/kg/hr, or find the units/hr infusing from the rate.
Formula
Concentration (units/mL) = units in the bag ÷ mL in the bag
units/hr = units/kg/hr × weight (kg)
mL/hr = units/hr ÷ units/mL
How to calculate it step by step
- Find the concentration. The usual mix of 100 units of regular insulin in 100 mL is 1 unit/mL, so mL/hr equals units/hr.
- For a weight-based order (diabetic ketoacidosis protocols often use 0.1 or 0.14 units/kg/hr), multiply by the weight in kg.
- Divide the units/hr by the units/mL.
Worked examples
Example 1. A regular insulin infusion of 100 units in 100 mL is running at 5 mL/hr. How many units per hour is the patient receiving?
- Concentration: 100 ÷ 100 = 1 unit/mL.
- 5 mL/hr × 1 unit/mL = 5 units/hr.
Answer: 5 units/hr
Example 2. A regular insulin infusion of 250 units in 250 mL is running at 12 mL/hr. How many units per hour is the patient receiving?
- Concentration: 250 ÷ 250 = 1 unit/mL.
- 12 mL/hr × 1 unit/mL = 12 units/hr.
Answer: 12 units/hr
Rounding
Round the pump rate to the tenth of a mL/hr.
Common mistakes
- Using an insulin other than regular insulin: only regular insulin is given by continuous IV infusion.
- Forgetting that insulin binds to the IV tubing: many protocols prime and waste a volume of the mixture through the tubing first.
Nursing safety points
- Insulin is a high-alert medication: independent double check, hourly blood glucose, and potassium monitoring per protocol (insulin moves potassium into the cells).
- In diabetic ketoacidosis, add dextrose to the IV fluids as the protocol directs when glucose falls, and continue insulin until the anion gap closes.
- Give subcutaneous insulin before stopping the drip, as ordered, to prevent rebound hyperglycemia.
Frequently asked questions
How do you calculate an insulin drip rate?
Divide units/hr by the concentration. With 100 units in 100 mL (1 unit/mL), 7 units/hr runs at 7 mL/hr.
What is 0.1 units/kg/hr for a 70 kg patient?
0.1 × 70 = 7 units/hr. At 1 unit/mL that is 7 mL/hr.