Converting plain to self-raising flour

SR flour

Catchy title eh?

A lot of UK recipes call for self-raising flour. Self-raising flour is nothing fancy – it’s just plain (all-purpose) flour with a chemical raising agent, baking powder, already in the mix.

Self-raising flour was invented by Bristol baker Henry Jones, who patented it in 1845. It played a role in phasing out the notoriously solid ship’s biscuits and replacing them with an alternative: chemically leavened “bread” baked fresh at sea or even on the battlefront. Apparently his work was championed by Florence Nightingale and I believe self-raising flour was used to bake “bread” in the Crimean War.

I’m not sure about “bread” made with SR flour – it’d be much more like soda bread or scone that real bread – but it’s useful stuff for cakes and the like. A lot of bakers, however, prefer to just use plain flour then add the raising agent separately. This makes sense, as the chemicals in raising agents can lose their potency making resulting cakes inconsistent. Or home bakers might just have run out.

If you don’t have an SR flour, it’s easy to convert plain and use that in its place. Though as with so many of these things, online information isn’t always in agreement. So I’m going to work it out for myself.

Varying sources say: add 1 teaspoon to 110g, or 2 teaspoons for 150g (1t to 75g), or 2 1/2 to 500g flour (that is, 1t to 200g), and, in that strange world without sane metric measures, another says 2 teaspoons to a cup.

Converting one US cup of flour into grams is open to disagreement too. Online sources give the flour weight as between 120g and 150g. I’ve got a cup measure – marked as 236.64ml, the customary US cup size* – and in a very scientific experiment involving filling it with flour, tapping it to settle it then smoothing off the top, I got 144g. Then I did it again and got 133g. This variable is due to how compacted the powder is, and is one of the reasons using weighing your ingredients is, frankly, more accurate. So anyway, let’s say 140g. So 2t to one cup is 2t to 140g (or 1t to 70g).

Cup measures

Then there’s the whole question of how many grams are in a teaspoon of a powder like baking powder. Again, sources differ online. But a teaspoon is 5cc/5ml (even in the US it’s basically the same, 4.92892159375ml**). Doing another quick, very scientific experiment, I filled my 5ml teaspoon measure with baking powder, smoothed it off, and weighed it. I did the same with baking soda. Both came in at just shy of 5g, so 5g is good enough for me.

Now, I work in decimal and percentage terms, having grown up with silly old ounces and whatnot but left them behind when I discovered the comparitive simplicity of metric measures. It’s so much easier when you’re converting and scaling recipes too.

The percentages you want of the above suggestions of teaspoons per grams would be based on the combined weight of the two ingredients, ie how many percent is 5g (1t) baking powder of the 115g of flour plus baking powder?

Here are all the abovementioned amounts in percentage calculations:
5g of 75g = 5 ÷ 75 x 100 = 6.7%
5g of 80g = 5 ÷ 80 x100 = 6.3g
5g of 115g = 5 ÷ 115 x 100 = 4.3%
5g of 205g = 5 ÷ 205 x 100 = 2.4%
(figures rounded)

Personally, I’m inclined to split the difference, and indeed some older notes of mine say 4%, and another person online breaking it down comes out with 4.5%. So averaging out the above figures, you get 4.9%. For the sake of ease, let’s say 5%.

So if a recipe calls for 250g of self-raising flour, and you only have plain, you need 5% of that 250g to be baking powder. That’s 12.5g of baking powder. So 12.5g BP added to 237.5g plain flour makes 250g stand-in self-raising flour. Even a digital scale, however, doesn’t usually do half grams, so let’s say 12g to 238g. And if you really want to short-cut it, just use 2 well-filled teaspoons to the 238g.


Cup plain flour

* A US legal cup is 240ml, an Australian/NZ etc cup is 250ml.
** Technically a US teaspoon relates to another strange archaic measure – it’s 1/3 US fluid dram.


Filed under Baking, Flour & grain, Misc

37 responses to “Converting plain to self-raising flour

  1. It is clever and kind Virgos like you who make a difference in this world. Thank you very much for taking the trouble to enlighten us like this. Bravo!

  2. Oh you sound like me when I’m trying to convert US recipes to metrics, and I’ve gone with anything between 130 and 140 grams for a cup of flour. And don’t get me started on sticks of butter. (Ok Saturday rant over) 🙂

    • Just a micro-rant. Sticks of butter – *facepalm*.,,,

    • Janet T

      As an American home cook and cookery editor living in London for 40 years, I can explain butter “sticks”: in the US, butter is sold in 1-lb packages containing 4 “sticks” (oblong blocks) wrapped in greaseproof paper marked off into standard tablespoons (15ml, as in UK). So each stick weighs 4 oz, which conveniently also measures 1/2 cup. I agree that weighing flour is much more accurate than measuring by volume (American style). But if you want to measure by the cup method, never tamp down the flour or shake it to settle, just dip the cup into the flour bag and level off with a knife. (All American measures are level.) I find the painstaking calculations above to be unnecessary and confusing – we don’t need extreme scientific precision, after all!

      • When I lived in NZ, way before I even saw any digital scales, I did a lot of cup measure baking. I understand the ease of it, but these days, after a lot of baking experience and training, I don’t like it, I find it can be inconsistent.

        I disagree with you about precision: it’s important for making chemically leavened products, and making them consistently. I cannot understand how cups of flour that has different amounts of air in it could ever be consistent in terms of weight or mass.

        Bread-making is very different to cake-making. You could say breads and yeasted products are “biologically leavenend” as you’re using is a living organism. Bread-making is a process that’s much more organic in that you can – and have to – adjust as you go depending on environmental conditions (temperature etc).

      • Hi Janet T. How interesting. I never knew the reason why butter was measured in sticks before. I don’t have a problem with using American volumetric measures, especially sticks/tablespoons of butter but I do agree with Daniel that weight measurements are much more reliable.

        Like “homecookexplorer” I always convert an American recipe to grams the first time I use it then tweak the gram measurements subsequently if the results are not quite as I want them. It’s the flour measurement I find most erratic. Even after fluffing up the flour before measuring I also find different brands have slightly different densities.

        So all in all I think it’s much more reliable to use a good digital scale which measures down to 1 gram and has a tare facility. It’s so easy because you can measure accurately straight into your pan or mixing bowl. I think it’s actually easier than faffing about with cup measure which then have to be washed.

        I have lots of American cookbooks and they are now annotated with handwritten gram measurements. The King Arthur flour books are great though because they give both cup and weight (albeit avoirdupois) measurements. I like the video recipes by Stephanie Jaworski (Joy of because, although they are a bit long-winded, she always gives both volumetric and weight measurements.

      • I have read that the best way to measure out a cup of flour is to spoon it gently into the cup measure, sift it, and re-measure it, again using a spoon and cup measure. Dipping the cup into flour always results in more than you need.

      • Sounds kinda time-consuming when you can just use some electric scales!

      • Bev R

        Sorry, you’re totally wrong. Baking IS a science so why you go to the far ends of a you know what spooning out/flattening/tamping/shaking etc when a set of scales does it in one shot accurately, I will never understand.
        I’m totally facepalming here too 🤦‍♀️🙄
        BTW, thanks for this, I went with the 5% ratio and it worked a charm (I’d run out of SR flour and needed a banana loaf like now).

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  4. Different flours have different densities, so you really can’t predictably lay down a conversion formula.
    My approach is that when I have a recipe supplying ‘cups of flour’ I put my cup measure on the weigh scale, tare to zero, add the flour, note how many grams it is and make that adjustment in the recipe.

    • Interesting, but I’m not sure I agree with your reasoning. Surely if you’re combining ingredients based on weight, a formula is fine, as density has no bearing on weight. Density is only a problem if you’re doing things exclusively with cup measures etc…. Although I’m confusing myself now, as are we really talking about weight, or mass?

  5. Ed

    Many, many thanks for this helpful article! And the take-home figure of 5% is a bonus as it’s instantly memorable! Now I’m to raise my own flour for the purposes of some nice cheesy biscuits — yum!

    • You’re welcome. I agree, 5% is nice and straightforward.

      • Leebeloola

        Well I’m glad it’s not just me finding inconsistent answers to how much baking powder to put in. Have you experimented with the amount of baking powder since you wrote this? One of the issues I came across is that this is different in different countries and it can be different.

        I too find the volume measurements annoying. I like knowing exactly how much I’m using so if I make changes *cough* mistakes, I can adjust the other ingredients or I can learn from it. If I try to do that in a recipe with cups, I also have to convert from volume to weight. This is where I usually give up.

      • Yes, since you got this, it’s got me thinking I need to do some more experiments. Dunno when I’ll find the time though. The 5% came from a teacher at the National Bakery School in London, but as you say, different countries are different, possibly partly as plain/all-purpose flours in different countries will have different qualities too.

  6. Evie

    Thank you so much – this is so helpful. I couldn’t agree more about weighing ingredients carefully in baking – it pays to be accurate so you can be consistent.

  7. Thanks a lot for this! I could never remember the ratio but now I’ve got 5% well and truly stuck in my head because you’ve explained it so well.

    I too am a stickler for g over cups. It’s just leaves smaller margin for error especially when there are people all over the world that could be using your recipes.

  8. Nay

    I prefer using gram and ml. I don’t like using cup measurement.

  9. Reblogged this on The Best of It and commented:
    Trying really hard to adjust my brain to using measures by weight for baking, as I do believe I’ll get more consistent results in with both yeast and quick breads by weighing my dry ingredients each time. This is the best conversion conversation and thought process I’ve seen yet for making my own self-rising flour. Thanks for doing this work for us! I’ll give it a try with my own home-ground soft-wheat flour and see what happens.

  10. Pingback: The Magic Baking Powder Ratio | A Kitchen Cat

  11. Jean

    Hello ? I just don’t understand one thing.You said that 1 teaspoon per 70 grams then you said baking powder is 5 % of your flour.But 5 gr baking powder per 70 gr is not 5%.It is 6.6% right? Or am i doing wrong? Help me !!

    • Hi Jean. That was just one example as I was looking at all the disagreement. I then said, “Here are all the abovementioned amounts in percentage calculations:
      5g of 75g = 5 ÷ 75 x 100 = 6.7%
      5g of 80g = 5 ÷ 80 x100 = 6.3g
      5g of 115g = 5 ÷ 115 x 100 = 4.3%
      5g of 205g = 5 ÷ 205 x 100 = 2.4%
      (figures rounded)
      … So averaging out the above figures, you get 4.9%. For the sake of ease, let’s say 5%.”

  12. Carole jones

    Oh my goodness, use imperial measurements, metric too confusing!

  13. Breanne

    Thank you, thank you!

    As an American, who prefers to weigh up my ingredients, trying to follow a Mary Berry recipe – you’re a lifesaver!

    I hate trying to measure flour by volume. Going through all the nonsense about it being “lightly spooned” into the cup, never packed down or tapped to settle, then getting it absolutely level – bah! So imprecise.

    So I didn’t really even want to make a bigger batch of SR flour by using 1.5 teaspoons of baking powder per cup of regular flour and then weighing up 450g of that blend. Too risky.

    Thank you!

  14. Thank you for this! I was trying to find a weight-based recipe for making UK self-raising flour in the US, so this is perfect.

    One note, though: a US teaspoon is 1/3 of a US tablespoon. No need to bring fluid drams into it.

  15. Great post, thanks Daniel! I used it as a reference for a self raising flour calculator: that folk might find handy.

  16. Susan Leigh

    What about gluten free flour?? Do you find your formula for plain flour and baking powder still works?

  17. Snoop

    Like others before me, I just had to say thank you. Working in percentages makes life easier across all recipes. Looking forward to having a look round your site. Thanks again.

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