What the percentage does not tell you

The percentage is the proportion by weight of ingredients derived from the cacao bean: cocoa mass, cocoa butter and any added cocoa solids combined. A 70% bar is 70% cacao-derived material and 30% everything else, almost always sugar.

That is all it means. It is a composition statement, not a quality grade.

Two 70% bars can be composed very differently. One might be 65% cocoa mass and 5% added cocoa butter; another 50% mass and 20% added butter. The second is softer, milder and less bitter despite the identical number.

Since cocoa butter is nearly flavourless and cocoa solids carry the flavour, the split matters enormously and is never stated. Ingredient order gives a hint and the mouthfeel gives the answer.

Sugar is what masks defects. At 90% there is almost none, so the beans have to be excellent — and most makers put their best beans at 70%, not 90%, because that is where fine character reads most clearly.

Higher percentage also flattens aromatic range in practice. A great 70% is more interesting than a great 90%, and a mediocre 90% is close to unpleasant.

Use it to predict sweetness and nothing else. It tells you roughly how sweet the bar will be, which is genuinely useful for choosing between two bars from the same maker.

Across makers it predicts very little, because roast profile and conch time swamp it. Comparing a 70% from one maker with a 70% from another tells you about the makers.