What's the difference between Bread Flour and All-Purpose Flour?

Bread Flour: 12.00-13.50% protein, absorption 1.000×, hydration 65-78%. All-Purpose Flour: 10.50-11.70% protein, absorption 0.970×, hydration 60-72%.

Can I substitute Bread Flour for All-Purpose Flour 1:1?

Not directly. Absorption differs by 3.1%, so Bread Flour needs more water. Adjust hydration by 3% when substituting.

Which is better for open-crumb sourdough?

Bread Flour supports higher hydration (up to 78%), making it better suited to open-crumb hearth loaves than All-Purpose Flour (max 72%).

Side-by-side comparison

Bread Flour vs All-Purpose Flour

	Bread Flour	All-Purpose Flour
Protein	12.00–13.50%	10.50–11.70%
Absorption (× bread flour)	1.000	0.970
Hydration range	65–78%	60–72%
Category	refined-wheat	refined-wheat
Ash %	0.50	0.48

Bread Flour

Bread flour is the workhorse of hearth-style sourdough. Milled from hard red winter or hard red spring wheat, it provides the 12-13.5% protein content needed to develop the robust gluten structure that supports open crumb and high hydration doughs. The absorption multiplier is the industry baseline (1.000) — all other flour hydration behaviors are measured relative to bread flour. King Arthur's classic unbleached bread flour and Central Milling's Artisan Bakers Craft are the reference specs for US bakers. Use it as 100% of the flour in baguettes and country loaves, or as the base (70-90%) in whole-grain blends. Bread flour tolerates extended autolyse, long bulk ferments, and retarded proofs without losing structure.

All-Purpose Flour

All-purpose flour (AP) sits between cake flour and bread flour in protein content. At 10.5-11.7% protein, it produces softer sourdough with more tender crumb but less oven spring than bread flour. Absorption is ~3% lower than bread flour baseline. King Arthur's AP is the US reference (11.7% protein); Gold Medal and Pillsbury run slightly lower (10.5-11%). Use AP when you want a softer hearth loaf, a sandwich-style sourdough pan loaf, or when blending into enriched doughs like brioche. AP absorbs less water — recipes designed for bread flour need hydration reduced by ~3% when substituting AP.

Substitution math

When substituting Bread Flour for All-Purpose Flour in a recipe, adjust hydration by about 3% — add more water because Bread Flour absorbs more than All-Purpose Flour.