Yes — all-purpose flour is what the UK calls plain flour. Swap them 1:1, ideally by weight: 1 US cup = 125 g. Neither contains a raising agent. The two things worth knowing before you bake are the protein nuance and the self-raising trap — both below.
The advice you'll find on most blogs is that UK plain flour runs slightly weaker — lower protein — than American all-purpose. There's something to it: plenty of British plain flour sits around 8–10% protein, while US all-purpose typically spans 10–12%, and King Arthur's flagship all-purpose is a notably high 11.7%.
But check actual bags and the tidy rule falls apart: Doves Farm's organic plain flour lists 11 g of protein per 100 g — higher than many American all-purpose flours — while the same brand's unbleached plain lists 7.9 g. The spread within UK plain flour is wider than the average gap between countries.
What it means in practice: for cakes, biscuits, muffins, pancakes, and thickening, swap freely and don't think about it. For chewy cookies, pizza, and anything bread-adjacent where gluten does structural work, glance at the nutrition label — and if your plain flour reads under ~10 g protein, blend in some strong flour or use it outright.
The swap that actually ruins bakes isn't plain-for-all-purpose — it's grabbing self-raising flour because the American recipe said "flour." Here's the full name map:
| US name | UK name | Notes |
|---|---|---|
| All-purpose flour | Plain flour | This page — swap 1:1. |
| Self-rising flour | Self-raising flour | Close but not identical: UK self-raising usually carries no salt; US self-rising does. |
| Bread flour | Strong flour / strong bread flour | Both mean higher protein (12%+) for chew and rise. |
| Whole wheat flour | Wholemeal flour | Same product, swap 1:1. |
| Cake flour | No direct equivalent | Use plain flour minus 2 tbsp per cup, plus 2 tbsp cornflour — the standard workaround. |
Following an American recipe from a UK kitchen? The cup is the real enemy, not the flour name. A cup of flour scooped straight from the bag can weigh 30% more than one spooned and leveled — a bigger error than any US/UK protein difference. Convert once and weigh: 1 US cup of plain or all-purpose flour = 125 g, and our cups-to-grams converter handles any quantity.
Published values, quoted at the exact measure each source lists. Sources round differently and assume different fill techniques — which is why they rarely agree to the gram.
| Source | Listed measure | Weight |
|---|---|---|
| King Arthur Baking | 1 cup | 120 g |
CupOrGram standardizes on 125 g per cup (8 g per tablespoon, 3 g per teaspoon) and uses that single value on every page — how we reconcile the sources.
Yes. All-purpose flour (US) and plain flour (UK, Ireland, Australia, New Zealand) are the same product: white wheat flour with no raising agent. Substitute 1:1 in any recipe — by weight if possible, at 125 g per US cup.
Plain. All-purpose flour contains no raising agent. If a US recipe calls for self-rising flour, that's the one that maps to UK self-raising — with one catch: US self-rising usually includes salt and UK self-raising usually doesn't, so check whether the recipe adds salt separately.
Less than the folklore says. The common claim is that UK plain flour runs lower protein, and many bags do sit around 8-10% — but brands vary widely: Doves Farm's organic plain flour lists 11 g protein per 100 g while their unbleached plain lists 7.9 g, and King Arthur's all-purpose is a high 11.7%. The brand-to-brand spread is bigger than the country-to-country one, so for bread-adjacent bakes, read the bag rather than the flag — or reach for strong flour.
125 g per US cup, spooned and leveled — the same value we use for all-purpose flour across this site. If you're following an American recipe from a UK kitchen, converting the cups to grams once and weighing is more accurate than buying measuring cups.