Audited —·Last updated 31 Jul 2026·5 citations·Tier 2·0 uses

Self-Rising Flour Calculator

Turn plain flour into self-rising flour, or swap the other way. King Arthur's published ratio, in cups or grams, with the 21 CFR 137.180 leavening cap.

Self-Rising Flour Calculator

What do you need?
In the first mode this is the plain flour you have. In the second it is the self-rising flour the recipe calls for. In the third it is the plain flour the recipe calls for. The calculator converts grams to cups using the right density for whichever flour that is — 120 g per cup for plain, 113 g per cup for self-rising.
Measured in
Leavening basis
Read in the third mode only. The calculator subtracts what the self-rising flour already supplies and tells you the top-up, which is often zero — King Arthur's instruction in that case is simply to omit it.
tsp
Read in the third mode only. Self-rising flour is salted — 21 CFR 137.180 requires it — so the recipe's salt usually comes down too. The 0.25 tsp per cup used here is King Arthur's homemade-blend figure; commercial salt levels are not published.
tsp
Baking powder to add
1.5
In the two blend-building modes this is the baking powder for the blend. In the reverse mode it is the top-up left after the self-rising flour's own leavening is subtracted, and it is often zero. Either way it is baking powder you add.
Baking powder (grams)
6 g
Salt to add
0.25 tsp
Salt (grams)
1.5 g
Flour to measure (cups)
1
Flour to measure (grams)
120 g
Total blend weight
127.5 g
Stands in for (cups of self-rising)
1
Leavening as % of flour
5.00
Against the federal standard
Leavening is 5% of the flour weight. 21 CFR 137.180 caps commercial self-rising flour at 4.5 parts acid-reacting substance plus sodium bicarbonate per 100 parts flour — baking powder also contains starch, so its reactive fraction is below this figure.
Summary
Whisk 120 g (1 cup) all-purpose flour with 1.5 tsp (6 g) baking powder and 0.25 tsp (1.5 g) table salt — 127.5 g of blend, standing in for 1 cup of self-rising flour.

Background.

Self-rising flour is plain flour with the leavening and the salt already mixed in, and the ratio is published: King Arthur's Homemade Self-Rising Flour recipe is "1 cup (120g) King Arthur Unbleached All-Purpose Flour, 1 1/2 teaspoons baking powder, 1/4 teaspoon table salt", whisked together, yielding one cup. This calculator scales that ratio in both directions — from the plain flour you have to the blend you need, and from the amount of self-rising flour a recipe demands back to the plain-flour blend that replaces it — and it also handles the reverse substitution, where a recipe is written for plain flour and self-rising is all you own.

That third direction is the one that goes wrong. Self-rising flour brings its own baking powder, so a recipe's leavening has to come down or the result will taste soapy and collapse. King Arthur's instruction is blunt: "Omit the baking powder and salt from the recipe — it's already in the self-rising flour." The calculator computes the shortfall rather than assuming it: it works out what the flour supplies at the leavening basis you choose, subtracts that from what the recipe asks for, and reports the top-up. Very often the top-up is zero, and the page says so in words rather than leaving you to interpret a 0.

The leavening basis is a dropdown for a specific and documented reason. King Arthur's own two published figures do not agree. The homemade-blend recipe puts 1.5 teaspoons of baking powder in a cup of flour. Their substitution article says self-rising flour "will work just fine in recipes using about 1/2 teaspoon (and up to 1 teaspoon*) baking powder per cup of flour" — a third to two-thirds as much. The two statements are about different things, a blend you mix versus a bag you buy, but they imply different leavening loads and a calculator that quietly picked one would give you the wrong top-up. All three quoted figures ship as modes, each labelled with the sentence it came from.

There is a federal specification behind all this. 21 CFR 137.180 defines self-rising flour as "an intimate mixture of flour, sodium bicarbonate, and one or more of the acid-reacting substances monocalcium phosphate, sodium acid pyrophosphate, and sodium aluminum phosphate", seasoned with salt, from which "not less than 0.5 percent of carbon dioxide is evolved", and it caps the leavening: "The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used." The calculator reports your blend's leavening as a percentage of the flour weight and reads it against that 4.5-part figure. Read the comparison carefully, because the page is careful about it too: the cap governs the acid salt plus the bicarbonate, not whole baking powder, which also contains starch as a filler. King Arthur's blend is 5.0 percent baking powder by flour weight, which is above 4.5 — but its reactive fraction is lower, so the two figures are consistent and the page does not claim otherwise.

Two more things belong beside the answer rather than below it. A cup of self-rising flour is not a cup of plain flour by weight — King Arthur's chart gives 113 grams against 120 — because self-rising flour is milled from softer wheat. That is why replacing 226 grams of self-rising flour takes 240 grams of plain flour, and the calculator uses the correct density for whichever flour your number describes. And the protein differs too, about 8.5 percent against 11.7 percent, which King Arthur says gives "softer, lighter, more tender baked goods" and more spread in cookies. Adding baking powder to bread flour makes a leavened flour; it does not make Southern self-rising flour. If tenderness is the point, King Arthur's own baker's tip is to build the blend from pastry flour at 106 grams per cup instead.

What is self-rising flour calculator?

Self-rising flour — self-raising flour in British usage — is a soft wheat flour premixed with a chemical leavening system and salt. Its composition is a federal standard of identity in the United States: 21 CFR 137.180 requires flour, sodium bicarbonate, and one or more of monocalcium phosphate, sodium acid pyrophosphate or sodium aluminum phosphate as the acid-reacting substance, plus salt, and it requires the finished product to evolve at least 0.5 percent carbon dioxide by the prescribed Chittick-apparatus test. The combined acid-reacting substance and sodium bicarbonate may not exceed 4.5 parts per 100 parts of flour.

The home substitution reproduces that system with double-acting baking powder, which is itself a bicarbonate, an acid salt and a starch filler in one tin. King Arthur's published ratio is 1.5 teaspoons of baking powder and 0.25 teaspoon of table salt per cup (120 g) of all-purpose flour, and they state the blend substitutes 1:1 by volume for self-rising flour.

What the substitution cannot reproduce is the flour. Commercial self-rising flour is milled from soft, low-protein wheat — about 8.5 percent protein against all-purpose flour's 11.7 percent — and packs lighter at 113 grams per cup against 120. Adding leavening to a stronger flour gives a chewier crumb and a different spread. The range of validity is therefore quick breads, biscuits, pancakes and cobblers where the leavening does the work; it is a poor idea for anything where the gluten structure is the point.

The calculator is exact arithmetic on a published ratio. It cannot know how old your baking powder is, and stale baking powder is the commonest cause of a flat biscuit.

How to use this calculator.

  1. Pick the direction. 'I have plain flour' is for making a batch of blend. 'The recipe wants self-rising flour' is for scaling the blend to what a recipe asks for. 'The recipe wants plain flour' is the reverse substitution, where self-rising flour is what you have and the recipe's leavening needs adjusting.
  2. Enter the amount and choose cups or grams. The number means a different flour in each mode, and the calculator converts grams accordingly — 120 g per cup for plain flour, 113 g per cup for self-rising — so entering 226 g of self-rising flour correctly becomes 2 cups, not 1.88.
  3. Choose the leavening basis. Use King Arthur's 1.5 teaspoons per cup when you are mixing the blend yourself. Use the 0.5 or 1 teaspoon commercial figures when you are reasoning about a bought bag, because that is what King Arthur says such flour stands in for.
  4. In the reverse mode only, enter how much baking powder and salt the recipe calls for. The calculator subtracts what the flour supplies and reports the top-up, which will read 0 when the substitution is exact.
  5. Read the summary line for the instruction in one sentence, with both spoons and grams. Weigh if you can: a scooped cup of flour can be twenty percent heavier than a spooned one, and that error goes straight into the leavening ratio.
  6. Check the federal-standard line beside the result if you care about how your blend compares with a commercial product. It reports your leavening as a percentage of flour weight against the 4.5-part cap in 21 CFR 137.180, and it explains why a 5 percent baking-powder figure is not a violation of a 4.5-part limit on reactive salts.
  7. Before you bake, test the baking powder: half a teaspoon in a little hot water should fizz immediately. No arithmetic on this page can detect a tin that has gone flat, and that is the most common reason a substitution fails.

The formula.

BP = cups × b ; salt = cups × 0.25 ; top-up = max(0, BP_recipe − cups × b)
cups · flour volume (grams ÷ 120 for plain, ÷ 113 for self-rising)b · tsp baking powder per cup (1.5 | 1.0 | 0.5)BP · teaspoons of baking powder for the blendBP_recipe · baking powder the recipe already calls fortop-up · extra baking powder still needed in the reverse direction4 g · one teaspoon of baking powder (King Arthur)6 g · one teaspoon of table salt (King Arthur, 18 g/tbsp)

The ratio is volumetric, so everything starts by converting the entered amount to cups. Which density does that conversion depends on which flour the number describes: plain flour at 120 g per cup, self-rising at 113 g per cup, both from King Arthur's Ingredient Weight Chart. This matters — 226 g of self-rising flour is exactly 2 cups, and treating it as 226 ÷ 120 = 1.88 cups would under-leaven the blend by six percent.

Building the blend is then two multiplications: baking powder = cups x the basis figure in teaspoons, salt = cups x 0.25 teaspoon. Converting to grams uses 4 g per teaspoon of baking powder and 6 g per teaspoon of table salt, again from the same chart. For King Arthur's published single cup that gives 1.5 tsp / 6 g of baking powder and 0.25 tsp / 1.5 g of salt against 120 g of flour, and a total blend weight of 127.5 g.

The reverse direction is a subtraction with a floor. The self-rising flour supplies cups x basis teaspoons of baking powder and cups x 0.25 teaspoon of salt; the top-up is the recipe's figure minus that, or zero if the flour already supplies more than the recipe wants. The floor is applied to the unrounded value, so a recipe that matches exactly returns a true 0 rather than a rounding residue, and the summary sentence then says to omit the leavening entirely — which is King Arthur's own instruction for that case.

Rounding stage. Nothing is rounded at an intermediate step. Every quantity is carried in arbitrary-precision decimal arithmetic and rounded exactly once, at the point the result leaves the calculator, to ten decimal places.

Classification stage. One output classifies: the federal-standard line. The scalar driving it is the leavening percentage of flour weight, read unrounded, with a single edge at 4.5 — the figure 21 CFR 137.180 sets as the maximum combined weight of acid-reacting substance and sodium bicarbonate per 100 parts of flour. Both branches are worded to preserve what the cap actually governs. Above 4.5 the page says the cap applies to the reactive salts and that baking powder also contains starch, so its reactive fraction is lower; at or below 4.5 it says the blend is inside the limit even before allowing for the starch. In the blend-building modes the percentage is fixed by the basis alone and is independent of batch size: 5 percent at 1.5 tsp per cup, 3.33 percent at 1 tsp, 1.67 percent at 0.5 tsp.

One source difference is recorded rather than resolved silently. Baker Bettie publishes the identical volumetric ratio — 1 cup of flour at 120 g, 1.5 tsp baking powder, 0.25 tsp salt — but gives 7.5 g for that baking powder and 1 g for that salt, against King Arthur's 6 g and 1.5 g. King Arthur's chart is used here because it also supplies both flour densities, and mixing density sources inside one calculation would be worse than choosing one. The effect is 5.0 percent versus 6.25 percent leavening by flour weight; both sit above the 4.5-part figure, so the page's regulatory reading does not change either way.

A worked example.

Example

A cook has a cup of all-purpose flour and a recipe that wants self-rising. Working in cups with King Arthur's homemade basis, flourToUseCups is 1 and flourToUseG is 1 x 120 = 120 g. bakingPowderTsp comes out at 1 x 1.5 = 1.5 tsp, which at the chart's 4 g per teaspoon makes bakingPowderG 6 g. saltTsp is 1 x 0.25 = 0.25 tsp, which at 6 g per teaspoon makes saltG 1.5 g. Those are King Arthur's published figures for their Homemade Self-Rising Flour recipe, quoted rather than derived: one cup of flour at 120 grams, one and a half teaspoons of baking powder, a quarter teaspoon of table salt. Adding the three gives blendTotalG of 120 + 6 + 1.5 = 127.5 g, and yieldSelfRisingCups is 1, because King Arthur states the blend substitutes one for one by volume for self-rising flour. The last figure is the interesting one: leaveningPercentOfFlour is 100 x 6 / 120 = 5 percent, the baker's-percentage view of the blend. That is above the 4.5 parts per 100 parts flour that 21 CFR 137.180 permits in a commercial self-rising flour, so cfrCheck takes its second branch — and the wording matters. The regulation caps the combined weight of the acid-reacting substance and the sodium bicarbonate, not the whole spoonful of baking powder, which also contains starch as a filler. The reactive fraction of those 6 grams is therefore below 5 percent of the flour weight, and the two figures are consistent rather than in conflict. Scaling to a three-cup biscuit batch multiplies everything by three — 360 g of flour, 4.5 tsp or 18 g of baking powder, 0.75 tsp or 4.5 g of salt, 382.5 g of blend — and leaves the 5 percent leavening figure unchanged, because it is a ratio.

flour Unitcups
recipe Salt Tsp0.25
flour Amount1
leavening BasiskingArthurHomemade
recipe Baking Powder Tsp1.5
solve FormakeSelfRising

Frequently asked questions.

Is self-rising flour the same as self-raising flour?
They are the same idea under two spellings — self-rising in American usage, self-raising in British and Australian — but the products are not identical and neither are the conventions around them. In the United States self-rising flour has a federal standard of identity, 21 CFR 137.180, which specifies the leavening system (sodium bicarbonate plus monocalcium phosphate, sodium acid pyrophosphate or sodium aluminum phosphate), requires salt, requires at least 0.5 percent carbon dioxide to be evolved, and caps the reactive leavening at 4.5 parts per 100 parts flour. British self-raising flour is not defined by a comparable standard of identity, and it is conventionally regarded as containing rather less leavening and often no added salt. If you are following a British recipe with an American bag, or the reverse, this page's three leavening bases are the honest way to handle the uncertainty: they are quoted figures, and the calculator tells you what each implies.
Why does replacing 226 g of self-rising flour take 240 g of plain flour?
Because a cup of the two flours does not weigh the same. King Arthur's Ingredient Weight Chart gives all-purpose flour at 120 g per cup and self-rising flour at 113 g per cup — self-rising flour is milled from softer, lower-protein wheat and packs lighter. So 226 g of self-rising flour is 2 cups, and 2 cups of plain flour is 240 g. The ratio King Arthur publishes is per cup, and it is the cup that transfers, not the gram. King Arthur does also say the blend substitutes 1:1 by weight, which would give 226 g of plain flour rather than 240; the two statements cannot both be exactly true given their own density chart, and this page follows the volumetric route because that is the unit the ratio is written in. The difference is about six percent of the flour, which matters for a cake and not much for a cobbler.
My recipe calls for plain flour and baking powder, and I only have self-rising. What do I do?
Use the third mode. Measure the same volume of self-rising flour as the recipe's plain flour, then subtract what the flour already brings from what the recipe asks for. King Arthur's instruction for the common case is simply "omit the baking powder and salt from the recipe — it's already in the self-rising flour", and the calculator will report a top-up of 0 and say so in words when that is right. Where it is not right is a recipe with unusually heavy leavening: King Arthur notes that self-rising flour suits recipes using about half a teaspoon, and up to one teaspoon, of baking powder per cup of flour, so a recipe wanting two teaspoons per cup needs a top-up. Set the leavening basis to the commercial figure that matches your assumption about the bag, and the calculator will tell you how much.
Can I use baking soda instead of baking powder?
Not on its own, and the regulation explains why. Baking soda is sodium bicarbonate alone; it needs an acid to release carbon dioxide. 21 CFR 137.180 requires self-rising flour to contain sodium bicarbonate together with an acid-reacting substance — monocalcium phosphate, sodium acid pyrophosphate or sodium aluminum phosphate — precisely because the bicarbonate is inert without one. Double-acting baking powder is that whole system in one tin: bicarbonate, acid salt, and starch to keep them apart and dry. If you use soda alone in a batter with no acidic ingredient you get almost no lift and a distinctly soapy, metallic taste from the unreacted alkali. If your recipe already contains buttermilk, yoghurt, molasses or cocoa, soda can work — but that is a different formula, not a self-rising substitution, and this page does not compute it.
Why is the blend 5% baking powder when the federal limit is 4.5 parts?
Because the two figures measure different things, and the page is careful to say so rather than implying King Arthur's recipe breaks a regulation. 21 CFR 137.180 caps "the combined weight of such acid-reacting substance and sodium bicarbonate" at 4.5 parts per 100 parts of flour. That is the reactive chemistry only. Double-acting baking powder is not pure reactive chemistry: it also contains starch, which keeps the acid salt and the bicarbonate from reacting in the tin and absorbs moisture. So 6 grams of baking powder in 120 grams of flour is 5 percent of the flour weight as baking powder, while the acid salt and bicarbonate inside it come to less than that — and the two are consistent. The page reports the 5 percent and the 4.5 and explains the gap, which is the honest presentation; asserting a specific starch fraction would be a guess.
Can I mix a big jar of this and keep it?
Yes — King Arthur's recipe explicitly permits it, and the practical caveats are about mixing and age rather than safety. Whisk thoroughly before each use: baking powder and salt are denser than flour and will settle toward the bottom of a jar that has been carried around, which leaves the top of the jar under-leavened and the bottom over-leavened. And watch the date. Baking powder loses strength over months, faster in a humid kitchen, and no calculator can detect it. Test a suspect tin with half a teaspoon in a little hot water; it should fizz immediately and vigorously. Commercial self-rising flour has the same problem — it is a perishable product in a way plain flour is not, which is one reason many bakers prefer to blend it on demand from the ratio on this page rather than keep a bag.
Will adding baking powder to bread flour give me real self-rising flour?
It will give you a leavened flour, but not the thing a Southern biscuit recipe means by self-rising flour, and the difference will show. King Arthur puts self-rising flour at about 8.5 percent protein against all-purpose flour's 11.7 percent, and describes the consequence directly: the lower protein "results in softer, lighter, more tender baked goods", with more spread in cookies. Bread flour is higher still. Leavening and protein are independent variables, and this page only substitutes the first. If tenderness is what you are after, King Arthur's own baker's tip on the recipe is to build the blend from pastry flour — 8.0 percent protein, 106 g per cup on their chart — or their pastry-flour blend at 10.3 percent, keeping the baking powder and salt amounts exactly the same. The calculator's ratio is unchanged; only the flour you pour it into is.

References& sources.

  1. [1]U.S. Government Publishing Office / U.S. Food and Drug Administration. 21 CFR § 137.180, "Self-rising flour", 2023 annual edition; retrieved 30 July 2026. The federal standard of identity and the source of every regulatory figure on this page: self-rising flour is "an intimate mixture of flour, sodium bicarbonate, and one or more of the acid-reacting substances monocalcium phosphate, sodium acid pyrophosphate, and sodium aluminum phosphate", seasoned with salt; "not less than 0.5 percent of carbon dioxide is evolved" under the prescribed Chittick-apparatus test; and "The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used." Independence: primary. Access: open.
  2. [2]King Arthur Baking Company. "Homemade Self-Rising Flour" recipe, current revision; retrieved 30 July 2026. The source of the blend ratio this calculator scales: "1 cup (120g) King Arthur Unbleached All-Purpose Flour, 1 1/2 teaspoons baking powder, 1/4 teaspoon table salt", whisked together, yield 1 cup. Also the source of the baker's tip to build the blend from pastry flour (8.0% protein) or pastry flour blend (10.3% protein) for a more tender result at the same leavening. Independence: primary. Access: open.
  3. [3]King Arthur Baking Company. "How to substitute self-rising flour for all-purpose flour (and vice versa!)" Article dated 30 March 2026; retrieved 30 July 2026. Source of the reverse-substitution rule — "Omit the baking powder and salt from the recipe — it's already in the self-rising flour" — of the two commercial leavening figures offered as modes on this page — self-rising flour "will work just fine in recipes using about 1/2 teaspoon (and up to 1 teaspoon*) baking powder per cup of flour" — and of the protein comparison, self-rising flour at about 8.5% against all-purpose at 11.7%, which "results in softer, lighter, more tender baked goods" and increases spread in cookies. Independence: primary. Access: open.
  4. [4]King Arthur Baking Company. Ingredient Weight Chart, current revision; retrieved 30 July 2026. Every gram constant in this calculator: all-purpose flour 1 cup = 120 g; self-rising flour 1 cup = 113 g; pastry flour 1 cup = 106 g; baking powder 1 teaspoon = 4 g; baking soda 1/2 teaspoon = 3 g; table salt 1 tablespoon = 18 g (hence 6 g per teaspoon); kosher salt 1 tablespoon = 8 g for Diamond Crystal and 16 g for Morton's. Independence: primary. Access: open.
  5. [5]National Institute of Standards and Technology. NIST Special Publication 811, 2008 edition — Guide for the Use of the International System of Units (SI). Table B.6 US customary capacity factors: teaspoon 4.92892159375 mL, tablespoon 14.78676478125 mL, cup 236.5882365 mL, and therefore the exact identities 1 cup = 16 tablespoons = 48 teaspoons that let a per-cup ratio be scaled to a fractional cup without drift. Independence: primary. Access: open.
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