The label says 13.5%. The wine can be 15%.

Short answer: most of what a wine label tells you is true within a tolerance you were never told about. The alcohol can be a point and a half off. The vintage can be a tenth some other year. The grape on the front can be a quarter something else. None of that is fraud; all of it is law. Here is what each number actually guarantees, so you know which ones to lean on and which to hold loosely.

Alcohol

The most trusted number on the bottle is the loosest. In the United States a wine labeled at 14 percent or under may legally be off by 1.5 points in either direction, so “13.5%” is a promise of somewhere between 12 and 15. Over 14 percent the tolerance narrows to one point. Europe is stricter at half a point, or 0.8 for sparkling, fortified and older bottle-aged wines. Producers also print in whole or half numbers and often reuse last year’s figure. That is why, when I show an alcohol figure I read off a label, I show it the way the label showed it, and when I have to estimate one I put a tilde in front of it (~13.5%) so you can tell the two apart. The tilde isn’t hedging. It’s the law’s own margin, made visible.

Vintage

“2022” means at least 95 percent of the wine came from 2022 if the label names an American viticultural area, and 85 percent if it names only a state or country. Europe sets it at 85. The rest can be older or younger wine blended in for balance or to stretch a short year. For most bottles this doesn’t matter. For a wine you’re buying because of the year, it’s worth knowing that the year is a floor, not a wall.

The grape

A varietal name in the United States guarantees 75 percent of that grape. A “Cabernet Sauvignon” can be a quarter Merlot and Petit Verdot without saying so. Oregon holds some varieties to 90. Europe requires 85. When a producer publishes the exact blend for a vintage, I’ll quote it. When they don’t, I’ll tell you the shape of the blend in words, because the percentages from a different year of the same wine are usually close, and close is exactly the kind of number that gets people in trouble.

Words that mean nothing, and one that means something

“Reserve” has no legal definition in the United States. Neither does “old vines,” “handcrafted” or “small lot.” They are adjectives. “Estate bottled” does mean something: the winery grew the grapes on land it owns or controls, crushed them, aged the wine and bottled it, all within the same appellation. Not a quality claim, but a real one.

The numbers that aren’t on the label

Drink windows come from critics, and a critic’s window is a forecast for a bottle stored perfectly, which yours probably wasn’t. Treat the window as a guess in a lab coat. Scores describe one glass on one afternoon in one person’s mouth. I’ll give you a read on a bottle, and I’ll give you what I think it’s worth, and I’ll say both as what they are: my opinion, not a measurement.

The verdict

Trust the vintage most, the grape next, and the alcohol least. Ignore “reserve.” Believe “estate bottled.” And treat any number that arrived without a tolerance as a number somebody rounded for you.

What I don’t know: what’s in your bottle. Nobody does without opening it. The label is a set of promises with margins, and the margins are the part worth remembering.