Tomato Slice Calories: Exact Count & Nutrition Facts

A single slice of tomato (approximately 18g) contains about 2.75 calories, making it an exceptionally low-calorie addition to any meal.

Curious about the exact calorie count in that slice of tomato on your sandwich or salad? You're not alone. Millions track their daily intake with precision, and understanding the nutritional value of even the smallest ingredients matters. Whether you're managing weight, following a specific diet, or simply making informed food choices, knowing the precise calorie content of common foods like tomatoes is essential.

Understanding Tomato Slice Calories: The Exact Numbers

When you're counting calories, every fraction counts. According to the USDA FoodData Central database—the most authoritative source for nutritional information in the United States—a medium raw tomato (about 148g) contains approximately 22 calories. But how does that translate to a single slice?

The answer depends on your slice thickness and tomato size. Most standard tomato slices used in sandwiches or salads weigh approximately 18 grams. Using the USDA data, we can calculate:

Tomato Portion	Weight	Calories
Medium whole tomato	148g	22
Standard slice (1/8 of tomato)	18g	2.75
Thick slice (steak tomato)	35g	5.25
Cherry tomato (whole)	12g	1.8

This precise measurement comes directly from the USDA's comprehensive food composition database, which nutrition professionals and researchers rely on for accurate dietary information. The calculation is straightforward: 22 calories ÷ 148g = 0.149 calories per gram × 18g = 2.75 calories.

Factors That Affect Tomato Calorie Count

While 2.75 calories is the standard count for a typical slice, several factors can cause slight variations:

• Tomato variety: Roma tomatoes tend to be slightly denser than beefsteak varieties
• Ripeness level: Fully ripe tomatoes contain marginally more natural sugars
• Water content: Tomatoes are 95% water, but this percentage varies slightly by type
• Slice thickness: Restaurant-style thick slices contain nearly double the calories of standard slices

According to a 2023 analysis published in the Journal of Food Composition and Analysis, the calorie range across common tomato varieties remains remarkably consistent, varying by less than 10% even between the densest heirloom varieties and watery standard grocery store tomatoes.

Tomato Nutrition: Beyond Just Calories

What makes tomatoes truly remarkable isn't just their low calorie count—it's the exceptional nutritional package they deliver for those few calories. A single slice provides:

• Vitamin C: About 3% of your daily value, supporting immune function
• Vitamin A: Approximately 2% of daily needs from beta-carotene
• Lycopene: This powerful antioxidant gives tomatoes their red color
• Potassium: Essential for heart health and muscle function
• Fiber: Small but meaningful contribution to daily fiber needs

Research from the Harvard T.H. Chan School of Public Health confirms that lycopene absorption increases when tomatoes are cooked or paired with healthy fats, though raw slices still provide significant antioxidant benefits. The Harvard nutrition database specifically highlights tomatoes as one of the top vegetable sources of this heart-healthy compound.

Practical Applications for Calorie-Conscious Eating

Understanding the minimal calorie impact of tomato slices opens up strategic possibilities for your diet:

• Volume eating: Add multiple slices to sandwiches without significant calorie impact
• Flavor enhancement: Replace higher-calorie toppings like cheese or avocado with tomatoes
• Salad foundation: Create substantial salads using tomatoes as a base ingredient
• Snack upgrade: Pair tomato slices with a small amount of healthy fat for balanced nutrition

Dietitians at the Mayo Clinic frequently recommend incorporating tomatoes into weight management plans precisely because they add volume, flavor, and nutrients with negligible calories. Their nutrition guidance emphasizes that foods like tomatoes help create satisfying meals within calorie limits.

Tomato Slices in Different Dietary Approaches

Whether you're following a specific eating plan, tomato slices fit seamlessly:

• Keto diets: With only 0.6g net carbs per slice, tomatoes fit within keto parameters
• Mediterranean diet: Tomatoes are a cornerstone ingredient in this heart-healthy approach
• Diabetes management: Low glycemic impact makes tomatoes diabetes-friendly
• Weight loss: Adds volume to meals without significant calorie cost

The American Diabetes Association specifically lists tomatoes as a "non-starchy vegetable" that people with diabetes can enjoy freely due to their minimal impact on blood sugar levels.

Common Questions About Tomato Calories

Does the calorie count differ between tomato varieties?

While minor variations exist, most common tomato varieties contain approximately 2.75 calories per standard slice (18g). Heirloom and beefsteak tomatoes may have slightly higher density, but the difference is negligible for calorie counting purposes.

Are cooked tomatoes higher in calories than raw slices?

Cooking concentrates tomatoes by removing water, so a cooked portion of the same weight would have slightly more calories. However, a single cooked tomato slice still contains only about 3-4 calories, remaining exceptionally low-calorie.

How many tomato slices equal 10 calories?

Approximately 4 standard slices (each 18g) would total about 11 calories. For precise tracking, 3.6 slices of standard size equal exactly 10 calories.

Do tomato slices have any fat or protein content?

Tomato slices contain negligible fat (less than 0.1g per slice) and minimal protein (about 0.3g). Their nutritional value comes primarily from vitamins, minerals, and antioxidants rather than macronutrients.

Can I eat unlimited tomatoes while counting calories?

While tomatoes are extremely low-calorie, consuming massive quantities could contribute to your daily intake. However, you'd need to eat approximately 36 slices to reach 100 calories, making them one of the most volume-friendly foods for calorie counters.