What is a 100 proof alcohol drink?
                                
                                
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                                    4 min read                                
                            
                                In the United States, a 100 proof alcohol drink is defined as containing exactly 50% alcohol by volume (ABV). The term 'proof' has historical roots stretching back to the 16th century, where a crude 'gunpowder test' was used to determine a spirit's strength for taxation.