Liquid – Atlas

If you’ve ever looked at a bottle of spirits and wondered what the number next to “proof” or “ABV” actually means, you’re not alone. Many people confuse alcohol proof with alcohol by volume (ABV), but while they are related, they are not the same.

In this post, we’ll break down the difference between proof and ABV, trace the history of proof in spirits, and show you exactly how to calculate both.

What is Alcohol by Volume (ABV)?

Alcohol by Volume (ABV) is the standard measure of how much pure alcohol (ethanol) is present in a drink compared to the total liquid volume.

• It’s expressed as a percentage.
• For example, if a bottle of gin is labeled 40% ABV, that means 40% of the liquid is pure alcohol and the rest is water and other compounds.

ABV is used internationally as the most reliable measurement of alcohol strength.

What is Alcohol Proof?

Alcohol proof is another way of expressing alcohol strength, but it depends on the country:

• In the United States: Proof is double the ABV.
  • Example: 40% ABV = 80 proof.
• In the United Kingdom (historically): Proof was based on an old system of “gunpowder test,” where spirits were tested to see if they could ignite. Today, the UK no longer uses proof—only ABV.
• In Europe and most countries: Only ABV is used on bottles.

So, if you see proof on a bottle, it’s most likely using the U.S. system.

Quick Conversion: Proof vs. ABV

Here’s a simple formula to remember:

• U.S. Proof = ABV × 2
• ABV = Proof ÷ 2

ABV (%)	U.S. Proof
40%	80 proof
45%	90 proof
50%	100 proof
60%	120 proof

Why Does Proof Exist?

The concept of proof dates back centuries.

• In the 18th century UK, alcohol was taxed based on strength. A “proof spirit” was one that contained 57.15% ABV—the point at which gunpowder soaked in the spirit could still ignite.
• In the U.S., proof was later simplified to just double the ABV, making it easier for consumers to understand spirit strength.

Today, ABV is more scientific and universal, while proof is often kept for tradition or marketing.

How to Calculate Alcohol Content

If you’re making cocktails, home-brewing, or just curious, you can calculate alcohol strength in a few ways:

1. From ABV to Proof

• Formula: Proof = ABV × 2
• Example: A whiskey with 47% ABV = 94 proof.

2. From Proof to ABV

• Formula: ABV = Proof ÷ 2
• Example: A rum labeled 151 proof = 75.5% ABV.

3. Estimating ABV in Cocktails

When you mix drinks, the ABV goes down because of dilution from ice, mixers, and juices.A simplified way to estimate:

• Multiply the ABV of each spirit by the volume you used.
• Add them together and divide by the total drink volume.

For example:

• 60 ml of vodka (40% ABV) + 120 ml of orange juice = 180 ml total.
• Vodka contributes 60 × 0.40 = 24 ml pure alcohol.
• 24 ÷ 180 = 13.3% ABV cocktail.

Final Thoughts

The key difference is simple:

• ABV is the actual percentage of alcohol.
• Proof is a traditional measure, mainly used in the U.S., that equals double the ABV.

If you want to understand how strong your spirits (or cocktails) are, stick with ABV—it’s the universal standard.