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Baking Soda vs. Baking Powder Redux

At least three times now I have seen responses to the question, "What is the difference between baking soda and baking powder?" answered with something like, "Baking powder makes baked goods rise up rather than spread, while baking soda does the opposite."1

To test this, I performed a simple experiment.  I made two mixtures.  Both contained 150 grams of all purpose flour.  To one of these, I added 1 teaspoon of baking powder.  To the other, I added one teaspoon of a mixture of baking soda, cream of tartar and cornstarch measured to contain the same amount of bicarbonate of soda as was in the baking powder2.

Each was then blended with 1 cup (228 grams) of water.  On an electric griddle, pancakes were cooked from these mixtures, measuring 3 tablespoons of batter per pancake and alternating them on the griddle to compensate for unevenness in the surface temperature.  Because they wouldn't be eaten, the pancakes were allowed to cook through from the bottom without flipping them.  Flipping might have caused random compression of the height of the pancakes.

After they were cooked, the pancakes were measured for average diameter and maximum height.  The results appeared as follows:

  Baking Baking
  Soda Powder
Average Diameter 81.3 mm 83.7 mm
Average  Height 15.3 mm 14.3 mm

So, contrary to the sources mentioned, the baking soda pancakes rose slightly higher while the baking powder pancakes spread slightly more.  I expect that a larger test than the simple one I did in my kitchen would show that the small differences which I found are not signigicant.

The lessons, as always, are to be skeptical of a lot of the "kitchen wisdom" you read and to try things out for yourself.

To see what the real differences are between baking soda and baking powder see Baking Soda vs. Baking Powder.  To see more kitchen myths, read KitchenSavvy Kitchen Science.

1. The sources are Kitchen Wisdom: Harrowsmith's Sourcebook for Cooks (1991); the Iowa Gazette, August 16, 2005; and a cooking website whose URL I can't recall.

2. To get the proper mixture for the baking soda mixture, I referred to the USDA National Nutrient Database for Standard Reference, to determine the sodium level in "baking powder, double-acting, straight phosphate" and in "baking soda".  The straight phosphate formulation was used as it most closely resembled the manufacturer's ingredients for the baking powder I had on hand.  Based on the sodium ratios, I mixed 3 1/3 teaspoons of baking soda, 6 2/3 teaspoons of cream of tartar and 2 teaspoons of cornstarch.  I then used 1 teaspoon of that mixture.  The ratio of baking soda to cream of tartar is recommended by Shirley O'Corriher in Cookwise: The Secrets of Cooking Revealed


What your experiment proves is that the baking soda mixture began releasing carbon dioxide mixture earlier than the baking powder causing it to begin rising earlier versus the baking powder spreading out on the griddle and then reacting. I find this to be a good assumption too. The reason for my assumption is that the 3 ingredients you used were probably more fresh than the ingredients the baking powder company used to make their mixture.To truly get a good baseline for baking powder versus home mixed baking powder you would have to cook maybe 20 to 100 pancakes and then take an average. I like your work though.

This website (, which appears first in a google search, says the opposite of what you do here regrading substitution. So which is correct? Thanks.

I used baking powder instead of baking soda in a bananna nut bread with buttermilk. What will happen?

Do baking sodas/powders react differently with gluten-free flours? Do I need to adjust the ratio of soda to flour when using gluten-free flours? Working on developing a gluten free Irish soda bread, and my dough is still coming out a little on the gummy side.

I think perhaps you missed the point: you should have simply added one teaspoon of baking soda to one batch and one teaspoon of baking powder to the other - people want to know about substituting equal volumes by accident, whereas you've added the ingredients necessary to transform that accidentally-substituted baking soda into the called-for baking powder....

Seems I'm not the only one! I used baking powder instead of baking soda in my cookies (even though it was sitting on the counter next to the powder!) I'm not sure what to do with these cookies either. They're supposed to be Christmas presents, and I'm really unsure if I should even bother cooking anymore of the batch! Eeek! Thanks in advance!

Just made a sugar cookie recipe that called for 1 tsp baking soda, used 1 tsp baking powder on accident, the dough is refrigerated tonite and I am planning to bake tomorrow. Should I even try to use the dough, is there anyway to salvage it, or should I just throw it out and start over. I would appreciate any help or feedback you can give me. Thanks!

I notice my baking powder had 3/97 dated on bottom of the can. I assume this is the expiration date. I'm in the middle of mixing ingredients for cake. How could I substitute with baking soda or is it safe to still use it???

Thanks in advance

I just made a 'double' batch of chocolate chip cookies & after the fact, realized I had used Baking Powder instead of Baking Soda. This lead me to look up what the actual differences are in the two items & saw some of your comments, so thought I'd send my findings for this recipe. (the only liquid in my recipe was eggs) The cookies turned out fine.. the 2 differences I noticed from previous batches (and this is one I used often) is that the bp cookies are more 'cakey' and not nearly as 'rich' in flavour as those made with B.Soda. And the B. Soda ones usually 'spread' out much more; altho the B. Powder ones didn't 'rise' very much.

The use of cornflour when making a baking powder substitute may be redundant, as its purpose in baking powder is simply to keep the soda and acid dry. If you are making your soda/acid mixture on the spot and adding it to your recipe right away, why bother with the starch? (Unless there is another function for the starch that I don't know about.)------------------------

You are right. The cornstarch in recipes for making homemade baking powder add it, as you say, to help keep ingredients dry and to give a mixutre that can be substituted measure for measure with commercial baking powder. In most cases, it can be left out if the mixture is being used right away and the volume used is adjusted to omit it. In this case, I added it to make sure that I was comparing equal volumes for measurement.Dave

How much baking soda should I use per cup of flour

I'm devising a coffeecake that will include yogart and I don't know whether to use baking soda or baking powder in the dry ingredients. I have been told to use b. powder with sweet milk and b. soda with buttermilk, sour cream, yogart, etc. Is this true and how much do I use per cup of flour

The acidity of the liquid (buttermilk vs sweet milk for example) is the primary difference in your results -- so if you used one or the other, the results will be completely different when you switch.[If that were true, then it would be a difference between buttermilk and sweet milk (or other liquids), not between baking powder and baking soda. Of course, adding the cream of tartar, which is a powdered form of tartaric acid, to the baking soda batter has the same effect as adding an acidic liquid once it dissolves in the water used.I see another potential experiment. -- Dave]

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