The fastest way to thicken canned soup is to stir in a cornstarch slurry: one tablespoon of cornstarch mixed with one tablespoon of cold water per cup of soup. But that’s just one option. Depending on what you have in your kitchen and what kind of texture you’re after, there are at least half a dozen reliable methods, from instant potato flakes to pureed beans to a handful of uncooked rice.
Cornstarch Slurry: The Quickest Fix
Cornstarch is the go-to thickener because it works in under two minutes and doesn’t change the flavor of your soup. Mix equal parts cornstarch and cold water in a small bowl until smooth. That paste is your slurry. For each cup of soup you want to thicken, use one tablespoon of cornstarch and one tablespoon of water.
Pour the slurry into your simmering soup while stirring constantly. It thickens almost immediately once it hits boiling temperature. The key mistake people make is dumping dry cornstarch straight into hot liquid, which creates lumps that won’t dissolve. Always mix with cold liquid first. If the soup isn’t thick enough after a minute or two, make another small batch of slurry and repeat. Cornstarch can lose its thickening power if you boil it for too long or stir too aggressively after it’s set, so add it near the end and keep the heat moderate.
Instant Potato Flakes
This is the secret weapon for creamy soups like chowders, potato soup, or anything with a starchy base. Instant mashed potato flakes dissolve into hot liquid and thicken it without any prep work. Use about one cup of flakes per four to five cups of liquid. Whisk them directly into the simmering soup, and you’ll see results almost immediately. Let it sit for a minute or two off heat if you want it even thicker.
Potato flakes add a subtle starchy body that feels more natural than cornstarch in cream-based soups. They also contribute a mild potato flavor, which blends in well with most savory soups but might taste off in something like a clear broth or tomato bisque. Start with less than you think you need; you can always add more.
Butter and Flour (Two Ways)
Flour and fat are the classic combination behind thick, rich sauces and soups. You can use this pairing two different ways depending on whether you’re starting fresh or rescuing a soup that’s already hot.
A roux works best at the beginning. Melt a tablespoon of butter in your pot, stir in a tablespoon of flour, and cook the mixture for a minute or two before pouring in the canned soup. The hot fat cooks out the raw flour taste and creates a smooth base. This is the method behind classic cream soups and gravies.
If your soup is already heated and you want to thicken it at the end, use a beurre manié instead. Knead equal parts softened butter and flour together on a cutting board or in a small bowl until you have a smooth paste. Drop small pieces of it into the hot soup and stir until each one dissolves. Because the flour is coated in fat, it blends into the liquid without clumping. Give the soup a few minutes of gentle simmering after adding it so the flour cooks through and loses its raw taste.
A Handful of Uncooked Rice
If you have 20 to 30 minutes and a bag of white rice, this method produces a beautifully thick, silky soup without any special ingredients. Drop a handful of uncooked white rice into your soup and let it simmer. As the rice cooks, it releases starch into the liquid, gradually thickening everything around it. Any white rice works: jasmine, basmati, short grain, long grain.
The rice grains themselves stay in the soup, which adds texture and bulk. If you want a smoother result, blend the soup with an immersion blender after the rice is fully cooked. This method works especially well with brothy canned soups that feel too thin and watery on their own.
Pureed Beans or Vegetables
Blending starchy ingredients you already have in the soup (or adding new ones) creates body without any flour, butter, or starch powder. Canned beans are perfect for this. White beans, black beans, cannellini, and navy beans all work well. Scoop out about a quarter of the beans or vegetables from the soup, puree them in a blender or food processor, and stir the puree back in. You can also use a potato masher right in the pot for a chunkier result.
If your canned soup doesn’t already contain beans, drain and rinse a half can of white beans and blend them with a splash of the soup broth before stirring them in. White beans have a neutral flavor that disappears into most soups. This method adds protein and fiber along with thickness, making it a good choice if you’re trying to turn a light canned soup into something more filling.
Breadcrumbs or Torn Bread
Bread has been used to thicken soups for centuries, and it works surprisingly well. Plain breadcrumbs dissolve almost instantly into hot soup. Add a little at a time, stirring between additions, until you reach the consistency you want. Store-bought plain breadcrumbs are fine, but skip anything with Italian seasoning or other added flavors unless that’s what you’re going for.
For a heartier approach, tear stale bread into chunks and simmer them directly in the soup. Use something plain like a country loaf or sourdough, and remove the crusts first. Avoid grainy or seedy breads because they won’t break down smoothly. The bread absorbs liquid and falls apart as it cooks, creating a thick, rustic texture. This is the technique behind classic Tuscan soups like ribollita, and it turns a thin canned soup into something that feels homemade.
Heavy Cream or Sour Cream
Dairy adds richness and body, though it thickens less dramatically than starch-based methods. The main challenge is preventing curdling. Never pour cold cream into boiling soup. Instead, take the pot off the heat or reduce it to low, then temper the cream first: whisk two to three tablespoons of the hot soup broth into the cold cream in a separate bowl, then stir that mixture back into the pot. Keep the temperature below 180°F (82°C) after adding the cream, and don’t let it boil again.
Letting the cream sit at room temperature for about 10 minutes before adding it also helps. The smaller the temperature gap between the cream and the soup, the lower the risk of curdling. Sour cream and yogurt follow the same rules but curdle even more easily, so temper them carefully and keep the heat gentle. Dairy works best as a finishing touch on soups that are already close to the thickness you want.
Xanthan Gum for Low-Carb Soups
If you’re avoiding starches and flour, xanthan gum thickens soup with virtually zero carbs and zero flavor impact. It’s extremely concentrated, so you need very little. Start with about half a teaspoon per four to six quarts of soup. Whisk it into a small bowl of soup first to prevent clumping, then stir that mixture back into the pot.
The most common mistake is using too much. Excess xanthan gum turns soup gummy and slimy rather than pleasantly thick. Add it in tiny increments and wait a minute between additions to see the full effect before adding more. You can find xanthan gum in the baking aisle of most grocery stores or in the gluten-free section.
Egg Yolks for Silky Richness
An egg yolk liaison is a classic French technique that gives soup a velvety, luxurious texture. Whisk one egg yolk with two to three parts cream by volume in a small bowl. Then slowly ladle a few spoonfuls of hot soup into the egg mixture while whisking constantly. This gradually raises the temperature of the eggs so they don’t scramble. Once tempered, pour the mixture back into the pot and stir gently over low heat. The soup should never exceed about 158°F (70°C) after the liaison goes in, and it should never boil. This method is best suited for elegant, smooth soups like cream of mushroom or cream of chicken where you want richness alongside thickness.