Is It Better To Thicken Soup With Flour Or Cornstarch?

When picking the right thickening agent for soup, there are two familiar contenders: cornstarch and flour.

Is one better than the other? Well, that depends on who you ask. Undoubtedly, both flour and cornstarch have their respective pros and cons. But, what they aren’t – is the same.

Regardless of what thickening agent you choose, the most important thing is to know how to use them and maximize their effectiveness while minimizing their individual issues.

Which Is Better: Cornstarch vs. Flour

In my experience, cornstarch is superior to regular flour in its effectiveness at thickening a dish. That said, you can use flour just fine, but you need to add more. Cornstarch or ‘cornflour’ in large quantities can interfere with the dish’s flavor more, introducing that ‘corny’ flavor, which you might not want. So if you need to do a lot of thickening, you should opt for all-purpose flour instead.

Both ingredients are similar in that they are both starch-based, so both work.

What you should do first is create a slurry. Take a bowl, add a tablespoon of flour or cornstarch, then add a tablespoon of boiling water at a time, and now stir. Do this until you reach the desired consistency. Congrats, you now have a thickening agent made into a slurry. Now you can add this to your soup – a little at a time. Once your soup reaches the desired thickness, you should stop adding the slurry, but keep stirring the soup until it reaches a nice even consistency throughout.

Note: To avoid clumps, you should add the flour first and spread it out in the mixing bowl as evenly as possible, then add the water in and stir thoroughly.

Remember, soups, stews, and similar will thicken as they cool. So if you reduce the soup’s heat toward the end of the cooking process, you’ll get a much better idea of how thick it is. This minor tweak can be beneficial to avoid over-thickening the soup.

Can You Use Plain Flour To Thicken Soup?

Is it possible to use all-purpose flour (plain flour) to thicken a soup or sauce? 

Of course, but you should avoid stirring it into the sauce or soup directly. This mistake is one of the common issues people run into when trying to thicken up a dish.

Instead, it would be best if you first made a slurry with flour and water. See the instructions in the section above to see how to do that.

Can You Use Self-Raising Flour To Thicken Soup?

Yes, you can use self-raising flour to thicken sauces and soups. 

As before, make sure you create a slurry with it and follow the same steps as you would with regular flour or cornstarch.

Note: Self-raising flour will thicken more quickly than regular plain flour, so add a little less than you usually would / only add a little at a time.


Both cornstarch and flour are effective at thickening soup when you take the proper steps. Remember, cornstarch absorbs more water and is better at thickening in general. However, flour is better when needed in large quantities to avoid upsetting the flavor of the dish.

Must-read related posts:

  • Corn Flour Substitutes: If you’re looking to thicken your soup with corn flour but don’t have any then check these alternative options.