Proof spirit refers to the strength of alcohol in a solution, commonly used in beverages and pharmacy.
Definition
Proof spirit contains 49.28% alcohol by weight or 57.1% alcohol by volume.
In the U.S., the formula for proof is:
Proof = 2 × Alcohol by Volume (ABV)
So, 50% ABV = 100 proof
Dilution Calculations
Pharmacists may need to dilute alcohol to reach a specific proof using Alligation or proportional dilution.
Example: To dilute 95% alcohol (190 proof) to 40% alcohol (80 proof), calculate how much water to add using simple dilution methods.