Bread flour vs cake flour
The two ends of the flour range, which is why this is the one flour comparison where the substitution genuinely does not work in either direction.
The short answer
These are the extremes, and every other flour comparison on this site sits between them. Bread flour is milled from hard wheat to the highest protein content in ordinary use, so it builds the strongest gluten network; cake flour is milled from soft wheat to the lowest, and in several markets chlorinated as well, specifically so that it will not. Swapping either way is the one flour substitution BakeHQ will not endorse: bread flour in a delicate cake gives a tough, tight crumb that no amount of gentle handling rescues, and cake flour in a lean loaf leaves nothing to hold the gas. Plain flour sits between them and is the honest substitute for either at a cost.
Where they differ
| Dimension | First | Second |
|---|---|---|
| Protein | The highest in ordinary domestic use, from hard wheat. | The lowest, from soft wheat. |
| What it is FOR | Building a network strong enough to hold fermentation gas for hours. | Avoiding building one at all, so the crumb stays tender. |
| Particle size | Ordinary. | Very fine, which changes how it hydrates and disperses. |
| Treatment | Untreated. | Chlorinated in some markets, which lets a batter carry more sugar and liquid. |
| Substituting one for the other | In a cake: tough, tight, and not fixable by handling. | In a lean bread: not enough network to hold the gas. |
Differences that do not matter
These are real distinctions that are unlikely to change your decision. They are listed so you can stop thinking about them rather than left out so the comparison looks decisive.
- Price. Slightly above plain flour. A speciality item in many countries.
Why the middle is the answer to both
Almost nobody has both of these in the cupboard, and the useful thing to know is that plain flour substitutes acceptably for either and badly for neither.
Going DOWN from bread flour to plain in a loaf costs some volume and some chew, and the loaf is still a loaf. Going UP from cake flour to plain in a sponge costs some fineness, and the cake is still a cake. Going the whole distance — one extreme for the other — is where it fails, because each flour was selected for the property the other was selected against.
That is also why the cornflour trick works in one direction only. Diluting plain flour with pure starch lowers its protein and approximates cake flour; there is nothing you can add to cake flour that puts protein back.
Related
Compares
The two ends of the protein range, and the one flour swap BakeHQ will not endorse in either direction.
The two ends of the protein range, and the one flour swap BakeHQ will not endorse in either direction.