You'll see alcohol concentration expressed three different ways depending on where you look: proof on American bottle labels, ABV on most modern packaging, and v/v on refractometer scales and scientific references.
They all measure the same thing — how much of the liquid is ethanol — but the numbers are different, which causes confusion.
Here's the quick conversion and when each one matters.
ABV (Alcohol by Volume)
ABV is the global standard. It expresses the percentage of a liquid's total volume that is pure ethanol. A bottle labeled 40% ABV means that 40% of the liquid inside is ethanol and the remaining 60% is water and other compounds.
ABV is what you'll see on virtually every bottle sold worldwide. It's also what cocktail recipes reference when they talk about a spirit's strength. When we say a cocktail has a 10% ABV, we mean 10% of the finished drink's volume is pure alcohol.
Where you'll see it: Bottle labels (nearly universal), cocktail recipes, our batch recipe ABV estimates.
Proof (U.S.)
Proof is an older system that's primarily an American convention. In the U.S., proof is simply ABV multiplied by 2. That's the entire conversion:
- 80 proof = 40% ABV
- 100 proof = 50% ABV
- 151 proof = 75.5% ABV
There's no complicated math. Divide the proof number by 2 and you have ABV.
The proof system dates back to an era when alcohol strength was literally "proved" by mixing it with gunpowder and lighting it. If the gunpowder still ignited, the spirit was at least 50% alcohol — or "100 proof." Anything below that threshold was "under proof." The mathematical definition (proof = 2 × ABV) was standardized later, but the terminology stuck.
Where you'll see it: U.S. bottle labels (alongside ABV), American liquor store signage, older cocktail books.
Important note: The British proof system is different from the American one and uses a different multiplier (roughly 1.75 instead of 2). British proof is rarely used today — virtually all modern labeling uses ABV — but if you're reading a vintage cocktail book from the UK, be aware that "100° proof" British means about 57% ABV, not 50%.
v/v (Volume by Volume)
v/v stands for "volume by volume" and is functionally identical to ABV — both express the percentage of a liquid's volume that is ethanol. The notation "40% v/v" means the same thing as "40% ABV."
The difference is context. ABV is the consumer-facing term on bottle labels. v/v is the technical and scientific notation used in laboratory settings, on refractometer scales, and in regulatory documents.
Where you'll see it: Alcohol refractometer scales (0–80% v/v), scientific literature, technical brewing and distilling references, our refractometer guides.
When you read an alcohol refractometer and it shows "40% v/v," that's the same as saying the liquid is 40% ABV or 80 proof.
The Conversion Table
| Proof (U.S.) | ABV (%) | v/v (%) | Common Example |
|---|---|---|---|
| 0 | 0 | 0 | Water, juice, soda |
| 22 | 11 | 11 | Aperol |
| 30 | 15 | 15 | Sweet vermouth |
| 40 | 20 | 20 | Kahlúa, triple sec |
| 50 | 25 | 25 | Campari |
| 60 | 30 | 30 | Some liqueurs |
| 70 | 35 | 35 | — |
| 80 | 40 | 40 | Most vodka, gin, rum, tequila |
| 86 | 43 | 43 | Many Scotch whiskies |
| 90 | 45 | 45 | Many bourbons |
| 100 | 50 | 50 | Bonded spirits |
| 114 | 57 | 57 | Cask-strength bourbon (common range) |
| 120 | 60 | 60 | Navy-strength gin |
| 151 | 75.5 | 75.5 | Bacardi 151, Lemon Hart 151 |
| 190 | 95 | 95 | Everclear (where legal) |
Why This Matters for Batch Cocktails
When you're making a single drink, you don't usually need to think about alcohol math — you pour 2 oz of bourbon and that's that. But for batch cocktails, especially for frozen drink machines, knowing the ABV of every ingredient lets you calculate the total alcohol content of the batch.
Frozen drink machines should be a final mixed batch close to 5–10% ABV to freeze properly. Above 10% and the alcohol prevents the mixture from reaching the right frozen texture timely. Knowing that your tequila is 40% ABV (80 proof) and your triple sec is 20% ABV (40 proof) lets you calculate whether your batch will cooperate with the machine. This is why it is so important to prechill your batch before pouring it into the frozen drink machine.
A quick example: if your 1-gallon (128 oz) batch contains 16 oz of 40% ABV tequila and 8 oz of 20% ABV triple sec, the total alcohol is (16 × 0.40) + (8 × 0.20) = 6.4 + 1.6 = 8 oz of pure alcohol. Divided by 128 oz total volume, that's 6.25% ABV — right in the sweet spot.
MixologyRecipe calculates this automatically on our batch recipe pages, but understanding the math helps when you're adapting your own recipes or troubleshooting a batch that won't freeze.
The One-Sentence Summary
Proof ÷ 2 = ABV = v/v. That's the whole conversion. ABV and v/v are the same number. Proof is double that number. Everything else is context.
For more on measuring alcohol content with a refractometer, see: Alcohol Refractometer vs. Brix Refractometer — Which One Do You Need?
