What is the difference between units/hr and mL/hr?

Units per hour is the pharmacological dose — the actual amount of drug delivered per hour. mL per hour is the physical pump rate — how fast the bag empties. The relationship depends on concentration: mL/hr = (units/hr) ÷ (units/mL). Both values are needed: units/hr confirms the dose is correct, mL/hr is what you program into the pump.

How is concentration calculated from the bag?

Concentration (units/mL) = Total units in bag ÷ Total volume in mL. For example, a bag containing 25,000 units of heparin in 250 mL gives 100 units/mL. This number is then divided into the desired units/hr to get the pump rate in mL/hr.

Why is heparin dosed in units rather than mg?

Heparin potency varies by batch and is standardized by bioassay in International Units (IU), not by mass. Dosing in units/hr ensures consistent anticoagulant effect regardless of the heparin source or lot number. The same logic applies to insulin (units) and other biologics.

What weight should I use for weight-based dosing?

Most heparin protocols specify actual body weight (ABW). Some institutions cap the weight used at a defined maximum (e.g. 100 kg) to avoid supratherapeutic dosing in obese patients. Always follow your institutional protocol and confirm weight basis with the ordering provider.

Is this calculator a substitute for clinical judgment?

No. This tool is a mathematical reference only. All IV orders must be verified by a licensed nurse, pharmacist, or physician before administration. Always double-check against the original order, the physical label on the bag, and your institution's protocol.

IV Units Per Hour Calculator

Enter your ordered dose (units/hr or units/kg/hr) and bag concentration to get the infusion pump rate in units per hour and mL per hour.

Infusion Parameters

Dose Type

Flat units/hr Weight-based

Ordered Dose

units/hr

Bag Concentration

Total Units in Bag

Total Volume (mL)

Enter infusion parameters and click Calculate Rate.

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Summary

This calculator converts a prescribed IV dose into the infusion pump rate in units per hour and mL per hour. Enter the ordered dose (as a flat units/hr value or a weight-based units/kg/hr value), the bag concentration (total units in total volume), and patient weight if needed. The tool applies the standard formula: Rate (units/hr) = Dose × Weight, then Rate (mL/hr) = Rate (units/hr) ÷ Concentration (units/mL). Results are for educational and clinical-support reference only; a licensed pharmacist or physician must verify all infusion orders before administration.

How it works

Select the dose type: flat units/hr or weight-based units/kg/hr.
Enter the ordered dose (e.g. 1,000 units/hr or 18 units/kg/hr for heparin).
If weight-based, enter the patient's weight in kg.
Enter the bag concentration: total units and total volume in mL.
The calculator computes units per hour, concentration in units/mL, and the pump rate in mL/hr.
Review the result panel and use the copy button to transfer the rate to your documentation.

Use cases

Calculate heparin infusion rate from a weight-based protocol (e.g. 18 units/kg/hr).
Determine insulin drip rate from a flat units/hr order.
Verify a pharmacist-prepared bag concentration against the ordered rate.
Cross-check an existing pump setting before administering a unit-dosed IV.
Support nursing students learning IV drip rate calculations.
Quickly convert between units/hr and mL/hr at the bedside.
Recalculate the pump rate after a bag concentration change.
Validate protocol-driven titration steps against the physical bag.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu

IV Units Per Hour Calculator

Infusion Parameters

Infusion Rate

Calculation Breakdown

Summary

How it works

Use cases

Frequently Asked Questions

IV Units Per Hour Calculator

Use the IV Units Per Hour Calculator

Infusion Parameters

Infusion Rate

Calculation Breakdown

Summary

How it works

Use cases

Frequently Asked Questions