Ethanol Preservative - Calculated by Volume or by Mass? - Please Help

Thank you in advance for helping!

We are using ethanol in a mouthwash formula as a preservative. 

A lot of literature says that 20% ethanol is needed to preserve a formula. 

When they say 20% ethanol, do they mean 20% of the volume or of the mass because the difference is significant?

Hope everyone is staying safe!!


  • PharmaPharma Member, Pharmacist
    20% v/v is usually enough to stop microbes from growing. However, it will not kill them.
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