Free tool
Alcohol by Weight (ABW) Calculator
Convert alcohol by volume (ABV) to alcohol by weight (ABW) and proof. ABW is always lower than ABV because ethanol weighs less than water, so the same volume percentage is a smaller weight percentage.
The formula
ABW = ABV / 1.267 (approximate); proof = ABV x 2
Standard approximation; exact ABW depends on the solution density at temperature. This tool uses the same calculation as the Spirit Sight platform. It is general information, not tax or legal advice.
What is the difference between ABV and ABW?
ABV is the percentage of alcohol by volume; ABW is by weight. Because alcohol is less dense than water, ABW is lower, roughly ABV divided by 1.267 for typical spirits.
How do you convert ABV to proof?
In the US, proof is exactly twice the ABV, so 40% ABV is 80 proof.
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