Tomatoes are one of the most versatile foods in the kitchen, but their calorie count can vary noticeably depending on whether you are eating raw cherry tomatoes, canned diced tomatoes, tomato paste, or sun-dried varieties. This tomato calories per ounce calculator takes the guesswork out of portion tracking by letting you choose the tomato form, enter your serving size in ounces or grams, and instantly see calories, carbohydrates, protein, and fiber.
Whether you are logging meals in a calorie-tracking app, building a low-calorie meal plan, or simply curious about how many calories are hiding in that handful of cherry tomatoes, this tool gives you reliable, data-based estimates. The underlying values are drawn from standard USDA nutrition references and common commercial product averages, so you can use the results with confidence for daily meal planning and nutrition tracking.
Perfect for students, home cooks, dietitians, and fitness enthusiasts, the calculator also includes handy portion presets like a medium tomato or a cup of cherry tomatoes, plus a quick unit converter between ounces and grams. Just pick your tomato type, enter your amount, and press calculate to see a full macronutrient breakdown in seconds.
🍅 Tomato Calories Per Ounce Calculator
Step-by-Step Guide
Using the calculator takes less than ten seconds. First, choose the tomato form that matches what you are eating — raw, cherry, canned, sauce, paste, or sun-dried. Next, enter the amount in ounces or grams. If you are measuring a typical portion, use the quick presets: a medium whole tomato (about 4.2 oz), a cup of cherry tomatoes (about 5.3 oz), or a single ounce. Finally, press Calculate to see calories, protein, carbohydrates, fiber, and sugar for your exact serving.
The results area also shows a short breakdown with the same portion converted to grams and the calories per 100 g, which is handy for comparing labels or logging into apps that use metric serving sizes. If you enter a different amount after calculating, just press the button again — there is no need to reset between calculations.
How It Works
Every value in this calculator is expressed as per-ounce nutrient data. When you enter your serving size, the tool multiplies the selected tomato form's per-ounce values by the number of ounces. If you enter grams, it first converts to ounces using the standard conversion factor: 1 ounce = 28.3495 grams.
The nutrient baselines are adapted from USDA FoodData Central entries for raw red tomatoes, cherry tomatoes, canned diced tomatoes, tomato sauce, tomato paste, and sun-dried tomatoes. Because whole raw tomatoes are about 94 percent water, they are naturally very low in calories — roughly 18 kcal per ounce. Sun-dried tomatoes, by contrast, have had most of their water removed, concentrating their sugars and fiber to about 258 kcal per ounce.
Here is a simplified formula for each result:
Calories = per-ounce calorie value × weight in ounces
Protein / Carbs / Fiber / Sugar = per-ounce nutrient value × weight in ounces
Reference Table: Tomato Forms Compared
| Tomato Form | Calories per 100 g | Carbs per 100 g | Fiber per 100 g | Protein per 100 g |
|---|---|---|---|---|
| Raw tomato | 18 | 3.9 g | 1.2 g | 0.9 g |
| Cherry tomato | 18 | 3.9 g | 1.2 g | 0.9 g |
| Canned diced tomato | 21 | 4.4 g | 1.1 g | 1.0 g |
| Tomato sauce | 24 | 5.3 g | 1.5 g | 1.1 g |
| Tomato paste | 82 | 18.9 g | 4.1 g | 4.3 g |
| Sun-dried tomato | 258 | 55.8 g | 12.3 g | 14.1 g |
These figures are approximate and may vary slightly between brands, especially for canned and sun-dried products that contain added salt, oil, or other seasonings.
Worked Examples
Example 1: A medium raw tomato
A medium tomato weighs about 4.2 oz. Using the raw tomato per-ounce value of 18 kcal, the calculation is 18 × 4.2 = 75.6 kcal. The same tomato provides about 3.8 g of carbs, 1.2 g of fiber, and 0.9 g of protein.
Example 2: 100 g of tomato paste
Tomato paste is concentrated, so 100 g packs roughly 82 kcal. In ounces, 100 g equals 3.53 oz. The calculator multiplies 82 × 3.53 to show 289 kcal per 100 g of paste — actually that is the per-ounce math: 82 kcal × 3.53 oz ≈ 289 kcal. Wait, this reveals a subtle point: the 82 kcal figure in the table is already per 100 g, not per ounce. The calculator's per-ounce values are lower. For our tool, 1 oz of tomato paste is about 23 kcal (82 ÷ 3.53), so a typical 3.53 oz (100 g) serving gives roughly 82 kcal.
To avoid confusion, always read the unit on the result screen: the calculator shows calories for your entered serving, plus a calories-per-100 g line in the breakdown for direct comparison with food labels.
Common Mistakes to Avoid
- Confusing tomato paste with raw tomato. Paste is five times more calorie-dense than fresh tomatoes. Always select the correct form.
- Ignoring added oil in sun-dried tomatoes. Many commercial sun-dried tomatoes are packed in oil, which adds roughly 120 kcal per tablespoon of oil. Choose oil-free dry-packed varieties for the numbers shown here.
- Using volume instead of weight. A “cup” of chopped tomatoes can vary by how finely you chop them. Weighing in ounces or grams is far more consistent.
- Forgetting the water content change after cooking. Simmering raw tomatoes reduces water and concentrates calories by weight, so cooked tomatoes without added ingredients will have slightly higher per-ounce calories than raw.
Frequently Asked Questions
Are tomatoes low in calories? Yes. Raw tomatoes are about 94% water and supply roughly 18 kcal per ounce, making them an excellent low-calorie, nutrient-dense food. A whole medium tomato often contains fewer calories than a single bite of cheese.
Do cherry tomatoes have the same calories as regular tomatoes? In most cases, yes — cherry and standard raw tomatoes are both close to 18 kcal per 100 g. Their smaller size can make portion counting less intuitive, which is why weighing is recommended.
Does cooking change tomato calories? Cooking without added fats changes the calorie density primarily through water loss. If you simmer tomatoes down to a thick sauce, a given weight of the sauce will contain more calories than the same weight of raw tomato because it is more concentrated. Adding oil, butter, or cream increases calories significantly.
Can this calculator help with keto or low-carb diets? Partially. Raw tomatoes contain about 3.9 g of carbs per 100 g, of which 1.2 g is fiber, leaving roughly 2.7 g of net carbs. Sun-dried and paste forms are higher in carbs, so they should be measured carefully. For more detailed macro planning, see the USDA FoodData Central database for official values.
Why do my app's numbers differ from these results? Calorie-tracking apps often use different database entries, and commercial brands can vary. The USDA-based values here are a solid reference, but when precision matters, check the nutrition label on the specific product you are eating.