Vial Dose to mL
Convert a prescribed dose (mg) into the volume (mL) to withdraw from a vial using the vial concentration (mg/mL).
Educational use only. Always verify vial label and follow local policy.
How it works
If a vial concentration is given as mg/mL and a dose is prescribed in mg, you can calculate the volume to draw in mL by dividing dose by concentration.
This is the same principle used across injections and infusions: amount = concentration × volume.
Formula
Worked examples
Example 1: Standard IV injection
Morphine 10 mg/mL. Dose 5 mg. How many mL?
Example 2: Paediatric dosing
Furosemide 20 mg/mL. Dose 4 mg. How many mL?
Example 3: High concentration (small volumes)
Atropine 100 mg/mL. Dose 1 mg. How many mL?
When this calculator is used
- •Converting a prescribed dose (mg) into a withdraw volume (mL)
- •IV/IM/SC medication preparation from vials
- •Paediatric or neonatal dosing where small volumes matter
- •Rapid checks in emergency/critical care
- •Second-check verification of manual calculations
Clinical safety reminder: Always verify the vial label concentration and perform an independent check. Use the smallest appropriate syringe for accuracy, especially for very small volumes.
Related calculators
Frequently asked questions
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.
References & sources
Institute for Safe Medication Practices (ISMP)
Medication safety guidance and error prevention
WHO Medication Safety
Global medication safety initiatives and guidance
ACSQHC Medication Safety Standard (NSQHS)
Australian medication safety standard
Clinical disclaimer: Educational use only. Verify labels and calculations per policy.