Miso soup is low in carbs. A typical bowl contains roughly 3 grams of total carbohydrates, making it a solid choice for keto, low-carb, and other carb-conscious diets. The exact number shifts depending on what goes into the bowl, but a basic miso soup with tofu and seaweed stays well within low-carb limits.
Carbs in a Standard Bowl
A standard serving of miso soup (about 9 ounces, the size you’d get at a Japanese restaurant) contains around 2.9 grams of total carbohydrates and 1.4 grams of dietary fiber. That puts the net carbs at roughly 1.5 grams per bowl. For context, most keto diets cap daily net carbs at 20 to 50 grams, so a bowl of miso soup barely makes a dent.
Most of those carbs come from the miso paste itself. One tablespoon of miso paste has 4.3 grams of carbs, 0.9 grams of fiber, and 1.1 grams of sugar. But a single bowl of soup typically uses only about one tablespoon of paste diluted in a large volume of broth, which is why the per-serving carb count stays so low.
Instant Miso Soup vs. Homemade
Instant miso soup packets are comparable to homemade. A single packet of Marukome instant miso soup, one of the most common brands, contains about 3 grams of total carbs and 2 grams of net carbs. That’s close enough to a fresh bowl that convenience isn’t costing you much in extra carbohydrates.
The bigger concern with instant packets is what else gets added during manufacturing. Some “dashi-included” miso pastes contain additives and are sterilized in ways that stop the activity of beneficial yeasts, which reduces the probiotic benefit that makes miso attractive in the first place. If you’re eating miso soup partly for gut health, homemade versions with fresh, unpasteurized miso paste are worth the extra effort.
What Raises the Carb Count
Plain miso soup is naturally low-carb, but add-ins can change the picture quickly. Here’s what to watch for:
- Noodles: Udon or soba noodles added to miso soup can bring 30 to 50 grams of carbs per serving. If you’re ordering miso ramen, that’s a different category entirely.
- Root vegetables: Sweet potato, carrots, and daikon radish are traditional in some miso soup styles (particularly tonjiru, a hearty pork and vegetable version). These add moderate carbs depending on quantity.
- Corn and rice: Some restaurant and instant varieties include corn kernels or rice, both of which raise the carb total significantly.
- Sweeteners: Mirin (a sweet rice wine) and sugar occasionally appear in restaurant or commercial preparations. These won’t double the carb count, but they add a few extra grams.
The classic combination of miso paste, dashi broth, tofu, wakame seaweed, and scallions keeps things minimal. Tofu adds roughly 1 gram of carbs per serving, and seaweed is essentially zero. Stick with that base and you’re looking at under 3 grams of net carbs.
White Miso vs. Red Miso
White miso (shiro) is fermented for a shorter time and tastes sweeter and milder. Red miso (aka) ferments longer and has a saltier, more intense flavor. White miso generally contains slightly more sugar because of its shorter fermentation, since the yeasts and bacteria have had less time to consume the sugars in the soybeans and grains. In practice, though, the difference per tablespoon is small, typically a gram or less. Neither variety will meaningfully affect your carb budget when used in normal soup quantities.
Making It Work on Keto
Miso soup is one of the most keto-friendly options you’ll find at a restaurant. At 1.5 to 3 net carbs per bowl, you can have it as a starter, a snack, or a light meal without worrying about your daily limit. It also provides sodium, which is helpful since low-carb diets tend to flush electrolytes faster than higher-carb eating patterns.
To keep your homemade version as low-carb as possible, use a simple dashi stock (made from dried kelp and bonito flakes, both essentially zero-carb), one tablespoon of miso paste per serving, and low-carb additions like tofu, seaweed, mushrooms, or leafy greens. Avoid starchy vegetables and anything with added sugar in the ingredient list. A bowl made this way comes in under 2 grams of net carbs and around 35 calories.