What's the difference between Bread Flour and Whole Wheat Flour?

Bread Flour: 12.00-13.50% protein, absorption 1.000×, hydration 65-78%. Whole Wheat Flour: 13.00-14.00% protein, absorption 1.075×, hydration 75-85%.

Can I substitute Bread Flour for Whole Wheat Flour 1:1?

Not directly. Absorption differs by 7.0%, so Bread Flour needs less water. Adjust hydration by 7% when substituting.

Which is better for open-crumb sourdough?

Whole Wheat Flour supports higher hydration (up to 85%), making it better suited to open-crumb hearth loaves than Bread Flour (max 78%).

Side-by-side comparison

Bread Flour vs Whole Wheat Flour

	Bread Flour	Whole Wheat Flour
Protein	12.00–13.50%	13.00–14.00%
Absorption (× bread flour)	1.000	1.075
Hydration range	65–78%	75–85%
Category	refined-wheat	whole-wheat
Ash %	0.50	1.60

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.

Whole Wheat Flour

Whole wheat flour contains the entire wheat kernel — bran, germ, and endosperm. Bran absorbs ~7.5% more water than refined flour, and the sharp bran particles cut through gluten strands, reducing effective gluten structure. Protein is higher by weight (13-14%) but functional gluten is lower. Result: whole wheat needs higher hydration (typically 80%+) and produces a denser, more flavorful crumb. WSU Bread Lab research shows hard red winter wheat varieties (Yecora Rojo, Warthog) mill into premium whole wheat for sourdough. King Arthur's Traditional Whole Wheat is a reliable reference.

Substitution math

When substituting Bread Flour for Whole Wheat Flour in a recipe, adjust hydration by about 7% — reduce water because Bread Flour absorbs less than Whole Wheat Flour.