Understanding What Percentage of a 90 Proof Bottle of Vodka Is Alcohol
                                
                                
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                                    4 min read                                
                            
                                A 90 proof bottle of vodka contains 45% alcohol by volume (ABV). While the term 'proof' has historical roots in gunpowder tests, the modern United States standard for distilled spirits is a straightforward calculation that can be easily understood.