The answers first. A medium tomato carries about 22 calories, under 5 grams of carbs, and roughly 19 percent of your daily vitamin C. That’s the whole headline, and it explains why no eating plan ever wrote a rule against tomatoes.
Now the full label, sized for the way people actually eat them. A slice on a sandwich, a Roma in the pan, a cup of cherries off the vine. Plus two facts hiding in the fine print. One is the pigment that made tomatoes famous. The other is the shortest “what’s NOT in it” section in nutrition writing.
The label a tomato would wear
The USDA baseline reads like this per 100 grams of raw tomato. 18 calories, 95 percent water, and 3.9 grams of carbohydrate (2.6 of them natural sugars, 1.2 fiber). Then 0.9 grams of protein and 0.2 grams of fat. Scale that one honest baseline and every size answers itself:
| The tomato you’re eating | ≈ Weight | ≈ Calories | ≈ Carbs |
|---|---|---|---|
| One thick slice | 20 g | 4 | under 1 g |
| One Roma | 60 g | 11 | 2.3 g |
| One medium tomato | 123 g | 22 | 4.8 g |
| One large tomato | 180 g | 33 | 7 g |
| One cup cherry tomatoes | 150 g | 27 | 5.9 g |
Two honest footnotes to the table. These are working averages, produce isn’t manufactured, and a sweeter, riper fruit runs a touch higher in sugar. And the numbers hold for every color and shape. The differences between varieties live in pigments and flavor, not meaningfully in calories.
For the carb-counting crowd: a medium tomato’s 4.8 grams include 1.5 grams of fiber, landing net carbs around 3.3 grams. That’s why tomatoes survive even strict low-carb cuts. The full keto verdict, with the serving math that matters there, lives in our keto deep dive.
What’s not in it (the shortest section on the site)
Fat: essentially none. Sodium: a few milligrams, nutritionally silent. Cholesterol: zero, as with all plants. This is the resume of what dietitians call a free food. Volume and flavor arrive at a calorie cost too small to track. It’s why “can I eat tomatoes on my diet” is nearly always a question with a one-word answer.
The vitamins and minerals that show up
The headline is vitamin C, about 19 percent of the daily value in one medium fruit. Behind it, tomatoes contribute meaningful potassium, vitamin K1, and folate. A respectable supporting cast for 22 calories. What each of those actually does for blood pressure, bones, and cells is the story of our health benefits guide. That’s where the “so what” of this label lives. This page is the what.
One mineral note for a specific audience. That potassium content, a virtue for most people, is exactly what kidney-diet readers ask about. The honest numbers live in our renal diet breakdown.
Lycopene: the number behind the fame
The tomato’s signature compound is lycopene, the red carotenoid pigment. The label figures run 1 to 8 milligrams per 100 grams of fresh tomato. The rule of thumb worth keeping: the redder the tomato, the more lycopene. That’s literal, the pigment IS the redness. The pale and green varieties in our color guide carry little, and the deepest reds carry most.
And here’s the fine-print surprise that reframes the whole topic. Ketchup measures 10 to 14 milligrams per 100 grams, more than fresh tomatoes. Concentration removes water and stacks the pigment. It’s the same math that powers our dried tomatoes. Cooked and concentrated tomato products are lycopene-dense in a way salads aren’t. Pairing any of them with a little fat, olive oil being the classic, meaningfully improves how much your body absorbs. Whether lycopene deserves its health halo is, again, the benefits guide’s story.
Raw vs cooked vs canned, on the label
The label shifts with the form, in predictable directions. Cooking removes water, so everything per-100-grams concentrates. Canned crushed tomatoes, pastes, and sauces carry more calories, carbs, and lycopene per spoonful than fresh. The totals stay modest in absolute terms. Watch exactly two things on processed labels. Added sodium, which is where canned products quietly diverge from the near-zero of fresh, and added sugar in ketchups and some sauces. Plain canned tomatoes with just salt remain one of the best label-to-price foods in the store.
For any amount this page didn’t cover, a specific gram weight, a can, a cup of sauce, our conversion calculator computes the calories along with the cups. And if you’ve ever wondered why a food this sugar-light is legally a fruit, that story has its own famous answer.
Frequently asked questions
How many calories are in a tomato?
About 22 calories in a medium tomato (123 grams) and 11 in a Roma. A thick slice runs 4, and a cup of cherry tomatoes about 27. The baseline is 18 calories per 100 grams, and every size scales from there.
How many carbs are in a tomato?
A medium tomato has about 4.8 grams of carbohydrate, including 1.5 grams of fiber, so roughly 3.3 grams net. Per 100 grams, tomatoes run 3.9 grams of carbs, of which 2.6 are natural sugars.
Are tomatoes high in sugar?
No. A medium tomato carries about 3 grams of natural sugar, less than a third of what an apple of the same size brings. The sweetness of a great tomato comes from balance and aroma more than sugar quantity.
What vitamins are tomatoes high in?
Vitamin C leads, about 19 percent of the daily value per medium tomato, with meaningful potassium, vitamin K1, and folate behind it. Plus lycopene, the antioxidant pigment tomatoes are famous for.
Do cooked tomatoes have more calories than raw?
Per 100 grams, yes, because cooking removes water and concentrates everything, calories, carbs, and lycopene alike. Per actual tomato, nothing changes. On processed products, the label lines worth watching are added sodium and added sugar. One number the label never shows is pH, and if that’s what brought you here, are tomatoes acidic has the real measurements.
Bottom line: 22 calories, under 5 carbs, 19 percent of your vitamin C, and effectively zero fat, sodium, and cholesterol. A label almost no food beats. The redder and more concentrated the tomato, the more lycopene rides along. What all of it does for your body is the next page: our full tomato nutrition guide and the benefits deep dive carry the story from here.