Proof to ABV converter
Convert US alcohol proof to ABV percentage and back. Includes a reference chart of common spirits.
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How to use Proof to ABV converter
Enter your figures
Fill in US Proof and ABV %. Values you change are used straight away, with no submit button.
Read the results
The totals and the breakdown below them update as soon as a value changes.
Start over any time
Nothing is saved on a server, so reloading the page clears everything.
What this tool does
Proof to ABV and back
US proof is exactly twice the ABV, so 80 proof is 40 percent. Type into either box and the other follows.
A chart of common spirits
The reference chart lists the usual bottlings, from 80 proof vodka up to cask strength, so a figure can be sanity-checked at a glance.
Runs fully in your browser with no upload and no sign-up
The conversion is arithmetic done in your browser, so nothing is uploaded and the page works with no connection.
Frequently asked questions
Why is proof double the ABV in the US?
The US adopted the simple rule that proof = 2 × ABV in 1848 by act of Congress. It was chosen for tax purposes - it is easy to calculate either way. Before that, "proof" referred to gunpowder tests: spirits that would still ignite gunpowder when mixed with it were considered "proved" to contain enough alcohol, roughly 57.15% ABV by the old test.
Why does the US still use proof?
Tradition, regulation, and marketing. The US Alcohol and Tobacco Tax and Trade Bureau (TTB) requires proof statements on distilled spirits labels. Many brands also use proof as a brand statement - "86 proof" sounds more distinctive than "43%". The system is so ingrained in American culture that changing it would be disorienting.
What is the minimum proof for spirits sold in the US?
To be labelled as "vodka", "whiskey", "rum", "gin" or other spirit categories, US federal regulations require a minimum of 40% ABV (80 proof). Some exceptions exist for certain categories and products bottled before modern regulations.
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