Infusion Rate Conversions
Infusion rate calculators for mL/hr, time-to-finish, and drip-rate conversions (gtt/min) — with formulas, worked examples, and FAQs.
mL/hr to mg/hr
Convert mL/hr infusion rate to mg/hr dose
mL/hr to mg/kg/hr
Convert mL/hr to weight-based mg/kg/hr dose
mL/hr to mg/min
Convert mL/hr infusion rate to mg/min dose
mL to mcg
Convert volume to micrograms for precision dosing
How Infusion Rate Calculations Work
Infusion rates describe how fast fluid runs through an IV line—whether via pump (mL/hr) or gravity drips (gtt/min). Understanding the relationship between volume, time, and rate is essential for accurate medication delivery and patient safety.
The core concept is simple: a given volume of fluid needs to be delivered over a specific time period. When using gravity infusions, you must also account for the drop factor (gtt/mL)—the number of drops the IV line delivers per millilitre. Always verify units (mL, hours, minutes, gtt/mL) and double-check your math before connecting any infusion.
Common Infusion Rate Calculations Explained
Infusion rate (mL/hr)
Use this to set or check an infusion pump rate from a total volume and time.
Example question:
A bag has 1,000 mL to run over 8 hours. What rate (mL/hr) should be set?
Worked example:
Answer: 125 mL/hr
Tip: Volume ÷ hours = mL per hour.
Drip rate (gtt/min) from mL/hr
For gravity infusions, convert mL/hr into drops per minute using the giving set drop factor (gtt/mL).
Example question:
An infusion is 120 mL/hr. Drop factor is 20 gtt/mL. What is the drip rate (gtt/min)?
Worked example:
Answer: 40 gtt/min
Tip: Divide by 60 first, then multiply by drop factor.
Time to finish (hours)
Estimate time remaining using the remaining volume and current rate.
Example question:
There is 600 mL remaining and the rate is 150 mL/hr. How long until it finishes?
Worked example:
Answer: 4 hours
Tip: Remaining ÷ rate = hours left.
When These Calculators Are Used
- •Setting or checking pump rates from volume and time (mL/hr)
- •Converting pump rates to gravity drip rates (gtt/min)
- •Estimating time remaining for handover and routine checks
- •Recalculating when volume/time/order changes
- •Double-checking units and arithmetic in high-workload settings
Clinical safety note:
Always confirm the order, delivery method (pump vs gravity), drop factor (gtt/mL), and local protocols. These calculators support calculation checking but do not replace professional judgement. Examples on this page are for calculation practice only.
Related Calculator Categories
Frequently Asked Questions
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.
Always confirm units and drop factor before calculating.