Quick answer: use bread flour for standard sourdough loaves (bâtards, boules, sandwich tins) and 00 flour where you want a softer, more extensible dough (pizza, focaccia, ciabatta). They are not interchangeable one-for-one, but they can be blended.
What is 00 flour?
"00" (doppio zero, "double zero") is an Italian grading that refers to how finely the flour has been milled - not to the protein content or where the wheat was grown. 00 flour is milled to a talc-like fineness, which means it hydrates fast, forms a very smooth dough, and produces a light, tender crumb.
Within 00 there are three broad tiers UK bakers should know:
- 00 Pizza (Caputo Blue "Pizzeria", 12-12.5% protein): classic Neapolitan pizza flour. Medium W-value, handles a 24-48 hour cold ferment. This is what you want for sourdough pizza.
- 00 Pane / Chef's Flour (Caputo Red "Cuoco", 13% protein): higher protein, higher W-value, absorbs more water. Made for long fermentation and higher-hydration doughs. Overlaps with what UK bakers call bread flour, but finer.
- 00 Pastry (Caputo Rinforzato Pasticceria, 9-10% protein): low protein, made for cakes and pasta. Don't use this for sourdough.
What is bread flour?
UK bread flour ("strong white bread flour") is milled coarser than 00 and contains higher protein - typically 12-14%. High protein means more gluten formation, which means more structure, more chew, and better oven spring for loaves. It absorbs water slowly compared to 00.
Common UK bread flours you'll find: Marriage's Strong White, Allinson Very Strong Bread Flour (14% protein), Doves Farm Strong White, Waitrose Duchy Strong White, Shipton Mill No. 4.
The four differences that matter
1. Protein and gluten development
Bread flour has slightly higher and more elastic protein than a typical 00 Pizza flour. That means bread flour dough is springier and has more structure. 00 dough is softer, more extensible, and stretches further without tearing.
2. Absorption
00 flour, being ultra-fine, absorbs water quickly - the dough feels hydrated within minutes of mixing. Bread flour absorbs slowly and often benefits from a 30 to 60 minute autolyse. If you swap 00 in place of bread flour without adjusting, you'll usually need to reduce water by 5-10% to compensate.
3. Fermentation tolerance
High-W (higher protein) 00 like Caputo Red is bred for long ferments - 24 to 72 hours cold. Standard bread flour tolerates 12-24 hours cold retard comfortably. Very-low-W 00 (pizza flour) is happy at 24-48 hours cold; more than that and it can start to break down.
4. Crumb and crust
Bread flour = chewier crumb, thicker crackling crust, more oven spring. 00 flour = softer, silkier crumb, thinner crust, more open irregular holes when hydration is right.
When to use each in sourdough
Use bread flour for:
- Standard sourdough boules and bâtards (60-75% hydration)
- Sandwich loaves
- Sourdough dinner rolls
- Rye or wholemeal blends (needs the gluten strength)
- Anything you want with real chew and a dark crust
Use 00 flour for:
- Sourdough pizza (Caputo Blue is the standard)
- Focaccia (softer crumb, easier stretch)
- Ciabatta (long extensibility, open crumb)
- Piadina and other flatbreads
- High-hydration open crumb loaves where you want maximum extensibility
Can you mix them?
Yes, and this is actually where many UK bakers land. A 50/50 or 70/30 bread flour to 00 blend gives you decent structure plus extensibility - great for hybrid loaves or for softening a bread that feels too chewy. If you're using UK bread flour that's too strong (14% protein), cutting it with 30% 00 tames it beautifully.
Two practical tests to run at home
If you've never compared them side by side, this is the single most useful thing you can do as a baker:
- The pizza test: make your usual sourdough pizza dough with Caputo Blue instead of bread flour. Same hydration, same schedule. Note the difference in stretch, blistering, and crumb.
- The autolyse test: mix 500g of each flour with 350g water, no starter, and rest 60 minutes. Poke both. The 00 will feel hydrated and slack; the bread flour will still feel a little dry and stiff. That's the absorption difference.
FAQ
Can I use 00 flour to feed my sourdough starter?
You can, but it's not ideal. Starters ferment best on flours with more bran and nutrients - wholemeal, rye, or a mix of white bread flour and wholemeal. 00 is too refined for a strong long-term feed. Use it in the bread itself, not the starter.
Is 00 flour the same as plain flour?
No. Plain flour is a general-purpose UK milling with lower protein (9-11%). 00 is defined by fineness, not protein. Some 00 flours have plain-flour-level protein (pastry 00) and some have bread-flour-level protein (Caputo Red). Read the packet.
What's the best 00 flour for sourdough pizza in the UK?
Caputo Pizzeria (Blue bag) is the classic choice and widely available on Amazon UK, Sous Chef, and specialty grocers. It handles a 24-48 hour cold cold ferment perfectly and produces authentic Neapolitan-style crust with proper leopard-spot blistering.
Why does my 00 dough feel too sticky?
Almost certainly because you're using the same hydration as you would with bread flour. 00 absorbs water faster, so it feels hydrated sooner but doesn't necessarily absorb more overall. Reduce the water by 5-10% or use higher-protein 00 (Caputo Red).
Can I substitute 00 flour 1:1 for bread flour?
Not quite. You can swap them by weight in most recipes but expect a softer, more extensible dough, a lighter crumb, and slightly less oven spring. For loaves you'll usually get better results with a 50/50 blend rather than a pure 00 swap.
Is 00 flour more expensive than bread flour in the UK?
Generally yes. UK bread flour runs approximately £1-£2 per kilo at supermarket level. Imported Italian 00 (Caputo, Molino Chiavazza, il Molino Rosso) is typically £3-£6 per kilo. Some UK mills now do their own "00 style" pizza flour at a lower price point.
Which UK stockists carry proper 00 flour?
Amazon UK, Sous Chef, Nifeislife, Pasta Evangelists, Waitrose (limited range), and independent Italian delis. For bulk (5kg+), Bakery Bits and Shipton Mill have UK-milled alternatives. See our full 00 flour buyer's guide for detailed picks.
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Related reading
- The Best 00 Flour for Sourdough in the UK (2026 Buyer's Guide) — honest reviews of every 00 flour worth buying, including Caputo, Molino Chiavazza and UK-milled alternatives.
- Dough Dough Sourdough Starter — our lab-verified 2-hour activation starter, ideal for pairing with a good 00 flour.
