Medical IV Rate & Drip Calculator
Calculate infusion rates in mL/hr and drops per minute (gtt/min).
Understanding IV Fluid Rate Calculations
In clinical practice, ensuring the correct administration of intravenous (IV) fluids is critical for patient safety. Nurses and medical professionals must accurately calculate how fast a fluid should flow to meet a prescribed dose over a specific timeframe.
The Formulas Used in this Calculator
This calculator utilizes two primary formulas standard in medical dosage calculations:
1. Flow Rate (mL/hr)
This is used when using an electronic infusion pump. The formula is:
Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hours)
2. Drip Rate (gtt/min)
This is used for manual gravity infusions where you must count the drops in the drip chamber. The formula is:
Drip Rate (gtt/min) = [Total Volume (mL) × Drop Factor (gtt/mL)] ÷ Time (minutes)
Common Drop Factors
The "drop factor" is determined by the administration set being used. It represents how many drops are required to equal 1 milliliter of fluid.
| Tubing Type | Drop Factor (gtt/mL) | Common Use |
|---|---|---|
| Macro-drip | 10, 15, or 20 | Routine adult fluid replacement |
| Micro-drip | 60 | Pediatric patients or precise medication delivery |
Calculation Example
Scenario: A physician orders 1,000 mL of Normal Saline to be infused over 8 hours. You are using a macro-drip set with a drop factor of 15 gtt/mL.
- Step 1: Calculate mL/hr. 1,000 mL ÷ 8 hours = 125 mL/hr.
- Step 2: Convert hours to minutes. 8 hours × 60 = 480 minutes.
- Step 3: Calculate gtt/min. (1,000 mL × 15 gtt/mL) ÷ 480 min = 31.25 gtt/min (rounded to 31 drops per minute).
Important Safety Note
Always double-check calculations with a colleague according to hospital protocol. Ensure the drop factor on the physical IV tubing package matches the value used in your calculation. If using a pump, verify that the rate is set correctly in mL/hr.