Calories in Flounder: Nutrition Facts & Serving Sizes
Per 1 fillet (163g)
Per 100g
Source: USDA FoodData Central, SR Legacy, March 2026.
Flounder is a lean flatfish with mild, slightly sweet white flesh and a delicate texture. One fillet (163g) contains just 114 calories, 20.2g of protein, and 3.1g of fat with zero carbohydrates. Per 100g, flounder has only 70 calories, making it one of the lowest-calorie protein sources available. The protein-to-calorie ratio is excellent, with 12.4g of protein per 100g. Flounder is also rich in selenium (26.6mcg per 100g), phosphorus (252mg per 100g), and vitamin D (2.8mcg per 100g), along with vitamin B12 at 1.1mcg. The low fat content (1.9g per 100g) puts it among the leanest fish options alongside tilapia and cod. Flounder is a practical choice for anyone in a cutting phase who needs to hit protein targets while keeping calories minimal. Its mild flavor makes it easy to season and prepare in multiple ways without overpowering other ingredients.
Nutrition Highlights
Calories by Serving Size
| Serving | Cal | Protein | Carbs | Fat | Fiber |
|---|---|---|---|---|---|
| 1 fillet (163g) | 114.1 | 20.2g | 0g | 3.1g | 0g |
| 1 oz, boneless (28g) | 19.9 | 3.5g | 0g | 0.5g | 0g |
| 3 oz (85g) | 59.5 | 10.5g | 0g | 1.6g | 0g |
| 100g | 70 | 12.4g | 0g | 1.9g | 0g |
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Full Nutrition Facts (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Calories | 70 | 4% |
| Protein | 12.4g | 25% |
| Total Fat | 1.9g | 2% |
| Saturated Fat | 0.4g | 2% |
| Total Carbohydrates | 0g | |
| Dietary Fiber | 0g | |
| Sugars | 0g | |
| Sodium | 296mg | 13% |
| Cholesterol | 45mg | 15% |
Vitamins & Minerals (per 100g)
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Saturated Fat | 0.4g | 0% |
| Cholesterol | 45mg | 15% |
| Calcium | 21mg | 2% |
| Iron | 0.2mg | 1% |
| Potassium | 160mg | 3% |
| Vitamin A | 10mcg | 1% |
| Vitamin D | 2.8mcg | 14% |
| Vitamin B6 | 0.1mg | 6% |
| Vitamin B12 | 1.1mcg | 46% |
| Magnesium | 18mg | 4% |
| Phosphorus | 252mg | 20% |
| Zinc | 0.3mg | 3% |
| Selenium | 26.6mcg | 48% |
| Folate | 5mcg | 1% |
| Niacin (B3) | 1mg | 6% |
% Daily Values based on a 2,000 calorie diet (FDA reference).
Health Benefits of Flounder
Flounder's standout quality is its combination of very low calories and solid protein content. At 70 calories and 12.4g of protein per 100g, it has one of the best protein-to-calorie ratios of any whole food. This makes it particularly effective during a calorie deficit when the goal is to maintain muscle mass while reducing body fat.
Selenium content at 26.6mcg per 100g is significant. A single fillet provides about 43mcg, exceeding the 55mcg daily recommended intake by nearly 80%. Selenium acts as a cofactor for the antioxidant enzyme glutathione peroxidase, protects thyroid tissue, and has been associated in research with reduced oxidative stress.
Vitamin D at 2.8mcg per 100g is relatively hard to obtain from food, as most dietary sources are limited. Flounder provides a meaningful contribution toward the 20mcg daily adequate intake. Vitamin D supports calcium absorption, bone density, immune function, and may influence testosterone production.
Vitamin B12 at 1.1mcg per 100g supports red blood cell formation and neurological function. Phosphorus at 252mg per 100g works alongside calcium to maintain bone mineral density and is involved in ATP energy production.
The low fat content (1.9g per 100g with only 0.4g saturated fat) keeps flounder suitable for heart-healthy diets and low-fat eating strategies without sacrificing nutritional completeness.
Dietary Considerations
Flounder is naturally gluten-free, dairy-free, and zero-carb, making it compatible with keto, paleo, Whole30, and low-carb diets. It is not vegan or vegetarian. At 70 calories per 100g and 12.4g of protein, it is an excellent choice for weight loss and body recomposition. The low fat content makes it easy to fit into tight calorie budgets. Sodium is 296mg per 100g naturally, which is worth noting for those on sodium-restricted diets. Flounder contains cholesterol at 45mg per 100g, typical for lean fish. It is a good source of complete protein for pescatarian diets. Mild flavor means it works with virtually any seasoning approach, from simple lemon and herbs to more complex marinades.
Daily Intake (100g)
100g of flounder provides 4% of a 2,000-calorie diet.
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Frequently Asked Questions
How many calories in flounder?
One flounder fillet (163g) contains about 114 calories. Per 100g, flounder has 70 calories. It is one of the lowest-calorie fish you can eat, making it excellent for calorie-controlled diets.
Is flounder good for weight loss?
Flounder is one of the best fish for weight loss. At 70 calories and 12.4g of protein per 100g, it provides filling protein for minimal calories. A full fillet gives you 20g of protein at just 114 calories, making it easy to hit protein targets without blowing your calorie budget.
How much protein in flounder?
A flounder fillet (163g) contains 20.2g of protein. Per 100g, flounder provides 12.4g of complete protein with all essential amino acids. It is a solid lean protein source for any fitness goal.
How does flounder compare to tilapia and cod?
Flounder (70 cal/100g), sole (70 cal/100g), and cod (82 cal/100g) are all very lean white fish with similar nutrition profiles. Tilapia (96 cal/100g) is slightly higher in calories. All are excellent lean protein choices. The differences are minimal and mostly come down to flavor preference and availability.
Is flounder high in mercury?
Flounder is considered a low-mercury fish, similar to tilapia and cod. It is safe to eat multiple times per week. Low-mercury fish are particularly recommended for regular consumption compared to high-mercury options like swordfish or shark.
Is flounder keto-friendly?
Yes. Flounder has zero carbohydrates, making it fully compatible with keto and low-carb diets. Its low fat content means you may need to add healthy fats when cooking it on a ketogenic diet to meet your fat macros.
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