Sometimes
Best ratio: Swap like for like by weight, but leave out any baking powder or bicarbonate the recipe adds — self-raising already contains roughly 2 tsp of raising agent per 200g.
Whether you can use self-raising in place of plain flour depends entirely on whether the recipe wants a rise. Self-raising is just plain flour with raising agent (and usually a little salt) already blended in, so it behaves very differently in different jobs.
When it’s fine
If you’re making something that’s supposed to rise — a cake, muffins, scones, pancakes — and the recipe adds baking powder, you can usually use self-raising and leave the added raising agent out. Self-raising contains roughly 2 teaspoons of baking powder per 200g, so you’d otherwise be doubling up and risking a cake that rises fast then sinks.
When to avoid it
Self-raising is a bad idea anywhere a rise is unwanted: pastry turns puffy and tough, sauces and roux thickened with it go cakey and can taste of raising agent, and coating batters puff oddly. For those, use plain flour (or cornflour to thicken).
The bottom line
Reach for self-raising in risen bakes and remember to drop the extra baking powder; keep plain flour for pastry, sauces and savoury cooking.
When it works
- Cakes, muffins, scones and pancakes where you'd be adding baking powder anyway.
- Recipes whose added raising agent is close to what self-raising already provides.
When it doesn't work
- Pastry, roux, batters for coating and anything used to thicken a sauce — the rise makes them puff or turn cakey.
- Yeast breads, where the extra raising agent interferes.
Taste & texture difference
In bakes meant to rise it's barely noticeable; in things that shouldn't rise it causes puffing, a spongy texture and sometimes a faint bitter, soapy taste from the raising agent.