For UK home bakers, the best flour for sourdough is a strong white bread flour with at least 12% protein — Marriage's Finest, Shipton Mill Canadian, Allinson's Strong White, or Doves Farm Strong White all qualify. The decision after that comes down to grain blend, fermentation behaviour, and what loaf you're trying to bake. We've baked with every flour in this guide, and we've got favourites — but the honest answer depends on your shop, your kitchen, and your patience.
What makes a flour good for sourdough
What is the best flour for sourdough bread UK?
The best flour for sourdough bread in the UK is a strong white bread flour with at least 12% protein. Marriage's Finest (12.5%), Shipton Mill Canadian (14%), Allinson's Strong White (12%) and Doves Farm Organic Strong White (12%) all qualify. Strong protein lets the gluten hold the gas a long bulk ferment produces, which is what gives a sourdough loaf its open crumb and tall rise.
The two things sourdough needs from its flour
Food. Wild yeast and Lactobacillus eat starches and the sugars enzymes release from them. Wholemeal and rye flours carry more native microbes on their bran, which is why they kick a starter off faster. White flour has less microbial life but plenty of starch — once the community is built, it bakes beautifully.
Structure. A free-form sourdough loaf has nothing holding it up except its own gluten matrix. That matrix needs enough protein (specifically glutenin and gliadin) to trap the carbon dioxide a long bulk produces. Below 12% protein, the loaf will spread sideways instead of upward.
Why supermarket "plain flour" doesn't make sourdough
Can I use plain flour for sourdough?
You can, but it won't make a proper sourdough loaf. Plain flour is around 9–10% protein, which isn't enough gluten to hold the gas of a long bulk ferment — the loaf will spread flat in the oven rather than rise. Plain flour is fine for sourdough discard pancakes, crackers and crumpets, but for the loaf itself, stick to strong white bread flour at 12% or higher.
The role of bran, germ and ash
Bran is the outer layer of the grain — fibrous, mineral-rich, packed with microbes and enzymes, but mechanically sharp enough to cut gluten strands as the dough develops. Germ is the small, oily, vitamin-dense embryo of the grain — the part that goes rancid first. Ash content is what miller's-tech-speak uses to describe how much of the bran and germ is left in the flour: burn a sample, weigh the mineral residue. White flour ash is ~0.5%; wholemeal ash is ~1.4%. High ash = more flavour, more microbes, less consistent gluten.
Protein content — why 12%+ matters
Is strong bread flour the same as bread flour?
In the UK, yes — "strong flour" and "bread flour" mean the same thing. The term strong refers to gluten strength, not flavour, and it signals a high-protein flour (typically 12–14%) milled from hard wheat. American recipes sometimes distinguish "all-purpose" from "bread flour", but in the UK the equivalent of US all-purpose is "plain flour" (lower protein), and "strong" or "bread" flour is the sourdough choice.
Reading the side of the bag (UK labelling vs gluten strength)
UK flour bags state nutritional protein per 100 g — which is slightly higher than the gluten protein that actually develops in your dough. Elaine Boddy puts it well: "my flour is 13.3 g of nutritional protein per 100 g, but the actual gluten protein is 12.7%." The number on the bag is a reliable proxy — but the real-world gluten is always 0.5–1 percentage points lower.
The DEFRA Bread and Flour Regulations definition of wholemeal
The DEFRA Bread and Flour Regulations define wholemeal flour as flour from the entire wheat grain — bran, germ and endosperm all retained, nothing removed. If a bag says "wholegrain" or "stoneground" but not "wholemeal", check the ingredients. UK wholemeal is a regulated term; the others aren't.
A quick UK protein-content reference table
| Flour | Stated protein | Type | Where to buy | ~Price / kg |
|---|---|---|---|---|
| Marriage's Finest Strong White | 12.5% | Roller-milled | Most supermarkets, BakeryBits | £1.80 |
| Shipton Mill Canadian Very Strong | 14% | Roller-milled | Shipton Mill direct, Waitrose | £2.50 |
| Shipton Mill Organic No. 1 | 13% | Stoneground | Shipton Mill direct, wholefoods | £3.00 |
| Doves Farm Organic Strong White | 12% | Roller-milled | Most supermarkets | £2.20 |
| Allinson's Strong White | 12% | Roller-milled | Tesco, Sainsbury's, Asda | £1.40 |
| Bacheldre Watermill Stoneground Strong | 13% | Stoneground | Waitrose, Bacheldre direct | £3.20 |
| Wessex Mill Strong White | 13% | Stoneground | Wessex Mill direct, wholefoods | £2.80 |
| Matthews Cotswold Churchill Bread | 12.8% | Roller-milled | Matthews direct | £2.40 |
| Tesco Strong White | 12% | Roller-milled | Tesco own brand | £0.85 |
| Sainsbury's Strong White | 12% | Roller-milled | Sainsbury's own brand | £0.85 |
| Waitrose Strong Canadian | 13.5% | Roller-milled | Waitrose own brand | £1.65 |
| Asda Strong White | 12% | Roller-milled | Asda own brand | £0.80 |
UK supermarket flours compared (Tesco, Sainsbury's, Waitrose, Asda)
Tesco Strong White — the workhorse
Available in every Tesco at every size from 500 g to 1.5 kg. 12% protein is on the edge for sourdough — fine for everyday bakes, slightly less open crumb than the premium options. If you're baking weekly, you'll save £40 a year over branded flour with no loaf-quality penalty most people would notice.
Sainsbury's Strong White — the close second
Identical specification to Tesco in our bake tests. Slightly creamier crumb on some bakes, but indistinguishable in a blind test. Whichever you find on the shelf is fine.
Waitrose Strong Canadian — the premium supermarket option
The high-protein Canadian wheat lifts this above the other supermarket options. The crumb is more open, the oven spring taller, the crust crackles louder. Worth the extra 80p/kg if you've got a Waitrose nearby.
Asda Strong White — the budget choice that surprises us
Cheapest of the four. Performs identically to Tesco's. Don't snub the budget option — it's the same hard wheat, milled to the same spec.
Head to head — which supermarket flour wins
For everyday baking, all four are workable. Waitrose Strong Canadian is the clear quality winner; Tesco / Sainsbury's / Asda are essentially interchangeable at half the price. If your local shop only stocks one, that's the answer.
UK speciality mills — Marriage's, Shipton Mill, Bacheldre, Doves Farm
Marriage's Finest Strong White — our everyday default
Predictable, reliable, widely stocked. Marriage's Finest is the flour we reach for when we want a loaf we can trust. The crumb is balanced, the rise is consistent, the bake is forgiving. If we had to recommend one flour to a new baker, this is it.
Shipton Mill Canadian Very Strong — when you need oven-spring
The highest-protein UK strong flour we use regularly. The 14% protein produces a noticeably taller, more open crumb. Best when you want a show-off loaf. Slightly more expensive, considerably more rise.
Bacheldre Watermill Stoneground — for rye, wholemeal, character
Genuinely watermilled in Wales. The stoneground process retains more bran and germ, which adds nutty depth and faster fermentation. Less consistent batch-to-batch than roller-milled flour — which is part of the appeal. For wholemeal and rye blends, Bacheldre is the standard.
Doves Farm Organic Strong White — the organic standard
The supermarket-stocked organic option. Lower protein than the very-strong flours but reliably good for a balanced everyday loaf. The choice if "organic" matters to you and the local mill doesn't deliver.
A nod to Cotswold Flour. For the deepest grain-level knowledge, Matthews Cotswold Flour is the UK authority on flour for sourdough — their Churchill Bread Flour (12.8% protein) and stoneground spelt blends are excellent, and their content team has written more honestly about flour science than almost anyone in the UK. We bake with their flour. We also bake with Marriage's, Shipton Mill, and Tesco's own. The best flour is the one your shop reliably stocks.
Wholemeal vs strong white — when to use each
100% wholemeal sourdough — what to expect
A 100% wholemeal sourdough is denser, more deeply flavoured, and considerably trickier to bake than a white-flour loaf. The bran cuts the gluten matrix as the dough develops, so the crumb is tighter. The flavour is properly nutty and slightly malty. Excellent for a sandwich loaf; harder to nail as a round boule.
The 80/20 white-wholemeal blend — the everyday loaf
Our recommendation for almost every UK home baker: 80% strong white + 20% stoneground wholemeal. The white provides the gluten structure; the wholemeal adds flavour, microbes (faster fermentation), and a slightly richer crumb. The blend that taught most of us what a good sourdough should taste like.
Adjusting hydration when you add wholemeal
Bran absorbs more water than white endosperm. For every 10% of wholemeal you add, bump hydration by ~1 percentage point. A 75% recipe for all-white becomes 77% for the 80/20 blend, 80% for 50/50, 82–84% for all-wholemeal.
Adding rye, spelt or einkorn to your blend
Rye — 10–30% for depth
A small amount of rye (10–20% of the total flour weight) adds extraordinary depth without making the loaf significantly harder to handle. Above 30%, rye starts to dominate — the loaf gets dense, very tangy, and harder to shape. Start at 10%.
Spelt — 20–50% for malty sweetness
Spelt is an ancient wheat with a sweeter, softer character than modern wheat. Up to 50% spelt makes a beautifully nutty loaf with a tender crumb. Spelt gluten is more fragile than modern wheat's, so handle gently — over-kneading breaks it.
Einkorn — handle with care
The oldest cultivated wheat. Beautiful flavour, very fragile gluten. Best used at 10–20% in a blend with strong white — pure einkorn loaves are advanced territory. Source Cotswold Flour or Sharpham Park for the proper UK-grown stuff.
What about stoneground?
Stoneground vs roller-milled — the honest difference
Stoneground flours are milled slowly between two stones; the friction is gentler, the temperature lower, more of the germ and bran end up in the bag. Roller-milled flours are produced at scale, more consistently, with most bran and germ sifted out. Stoneground = more flavour, more microbes, more batch-variation. Roller-milled = predictable, reliable, slightly less character.
When stoneground wins (and when it doesn't)
Stoneground wins for: starter feeding (more microbes), flavour-led bakes, wholemeal and rye work, and anyone who values the small-mill ethics. Roller-milled wins for: consistency across bakes, beginners learning the basics, and anyone tracking precise hydration. Most home bakers should use both.
Best flour for beginners (and why)
Which flour should I use for sourdough?
For your first ten loaves, use a single bag of strong white bread flour at 12%+ protein and stick with it. Marriage's Finest is our usual recommendation because it behaves predictably and is widely stocked. Add 10–20% stoneground wholemeal once you've got a loaf you're proud of — the wholemeal speeds fermentation and deepens flavour without making the loaf harder to shape.
Our pick for your first ten loaves
Marriage's Finest Strong White Bread Flour. 12.5% protein, £1.80/kg, in most supermarkets. If you can't find Marriage's, swap to Allinson's Strong White (£1.40/kg, in every Tesco/Sainsbury's/Asda). Both are roller-milled, both behave predictably, both are forgiving of a beginner's timing errors.
A nod to Cotswold Flour — the UK authority on this
If you want the deepest UK flour knowledge, Matthews Cotswold Flour's blog is the place. Their Churchill Bread Flour (12.8%) and stoneground spelt are both excellent. We acknowledge them as the UK authority on flour for sourdough.
Clara: "I bake on Marriage's Finest most weeks, switch to Shipton Mill Canadian when I want a show-off crumb, and keep a bag of Bacheldre wholemeal in the cupboard for the 80/20 blend. One supermarket flour, one premium flour, one wholemeal — that's the kit."
Interactive Flour Selector
Which flour for you?
Protein content vs typical oven spring
12 UK flours plotted by stated protein percentage and typical oven spring (Hub bake logs, Somerset 2024–2026). The 12%+ cluster is the recommended range.
UK flour storage and shelf life
Where to keep a 1.5 kg bag of strong white
A cool, dry cupboard away from the hob. Inside the original bag is fine for 6 months; decant to an airtight plastic or glass container if you live in a damp kitchen. Strong white keeps 12+ months unopened, 6–9 months once opened.
When flour goes off (and how to tell)
Strong white rarely goes off in any obvious way — but the gluten weakens over 12+ months and the flour can absorb fridge smells. If your loaves get progressively flatter on the same recipe, suspect the flour bag.
Wholemeal and rye need stricter storage
The oils in the germ go rancid within 3–4 months at room temperature. Store wholemeal and rye in the fridge or freezer if you don't use them weekly. Rancid wholemeal smells like crayons — bin it.
Frequently asked questions
What is the best flour for sourdough bread UK?
The best flour for sourdough bread in the UK is a strong white bread flour with at least 12% protein. Marriage's Finest (12.5%), Shipton Mill Canadian (14%), Allinson's Strong White (12%) and Doves Farm Organic Strong White (12%) all qualify. Strong protein lets the gluten hold the gas a long bulk ferment produces, which is what gives a sourdough loaf its open crumb and tall rise.
Which flour should I use for sourdough?
For your first ten loaves, use a single bag of strong white bread flour at 12%+ protein and stick with it. Marriage's Finest is our usual recommendation because it behaves predictably and is widely stocked. Add 10–20% stoneground wholemeal once you've got a loaf you're proud of — the wholemeal speeds fermentation and deepens flavour without making the loaf harder to shape.
What flour to avoid in sourdough starter?
Avoid plain flour, self-raising flour, and cake flour for sourdough — all three are too low in protein (8–10%) to build the gluten structure a sourdough loaf needs. Self-raising flour also contains baking powder, which interferes with the wild fermentation. Bleached flours, common in the US but rare in the UK, can also slow a starter because the bleaching process kills surface microbes.
Is strong bread flour the same as bread flour?
In the UK, yes — "strong flour" and "bread flour" mean the same thing. The term strong refers to gluten strength, not flavour, and it signals a high-protein flour (typically 12–14%) milled from hard wheat. American recipes sometimes distinguish "all-purpose" from "bread flour", but in the UK the equivalent of US all-purpose is "plain flour" (lower protein), and "strong" or "bread" flour is the sourdough choice.
Can I use plain flour for sourdough?
You can, but it won't make a proper sourdough loaf. Plain flour is around 9–10% protein, which isn't enough gluten to hold the gas of a long bulk ferment — the loaf will spread flat in the oven rather than rise. Plain flour is fine for sourdough discard pancakes, crackers and crumpets, but for the loaf itself, stick to strong white bread flour at 12% or higher.
Is supermarket flour as good as speciality mill flour?
For everyday baking, yes — supermarket-own strong white flours at 12% protein produce perfectly good sourdough loaves. The difference shows up in flavour depth and consistency: speciality mill flours (Marriage's, Shipton Mill, Bacheldre) have slightly more character and more reliable batch-to-batch performance. Bake a loaf with both; decide which is worth the extra £1/kg to you.
Does organic flour make better sourdough?
Not by itself. Organic certification is about how the wheat was grown, not how it behaves in dough. Organic strong white flours work identically to non-organic at the same protein level. Choose organic if you want to; don't expect a different loaf.
What's next
If you're not sure which starter to build with which flour, our comparison of rye, white and wholegrain starters walks the choice. For the maths behind why higher-protein flour handles higher hydration, see sourdough hydration explained. The pillar tying it all together: the UK beginner's guide to baking sourdough bread.
