Tomatoes — calories & nutrition
By Jenny Updated
Tomatoes are one of the most versatile and nutritious foods in the British kitchen — and at just 18 calories per 100g, they're one of the most generous in terms of what you get for the calorie cost. A medium tomato weighing 120g delivers only 22 calories while providing useful amounts of vitamin C, potassium, and lycopene — the powerful antioxidant that gives tomatoes their red colour and has been linked in research to reduced risk of heart disease and certain cancers.
Lycopene is actually more bioavailable from cooked and processed tomatoes than raw ones, which means tinned tomatoes, passata, and cooked tomato sauces provide more of this beneficial compound than the same weight of fresh tomatoes. This is a rare case where the convenience food version of an ingredient is actually more nutritious than fresh — excellent news for anyone building meals around simple, budget-friendly ingredients.
On Slimming World, fresh, tinned, and passata tomatoes are all Free Foods and Speed Foods. This makes them extraordinarily useful as a base for low-calorie, filling sauces and soups. A quick pasta sauce made from a tin of tomatoes, garlic, onion, and herbs is completely Free, deeply satisfying, and takes fifteen minutes to make. Cherry tomatoes are a brilliant Free Food snack — a bowl of them with a pinch of flaky salt is genuinely enjoyable and calorie-negligible.
Tomatoes nutrition breakdown
| Portion | Calories | Carbs (g) | Fat (g) | Protein (g) | Fibre (g) |
|---|---|---|---|---|---|
| 1 medium tomato, ~120g | 22 | 4 | 0 | 1 | 1 |
| 100g | 18 | 3 | 0 | 1 | 1 |
| 6 cherry tomatoes, ~90g | 16 | 3 | 0 | 1 | 1 |
How Tomatoes compares
Calories per 100g
FAQs
How many calories are in a tomato?
A medium tomato weighing around 120g contains approximately 22 calories. Per 100g, fresh tomatoes are around 18 kcal. Six cherry tomatoes weighing about 90g deliver just 16 calories. Tomatoes are one of the lowest-calorie salad vegetables available, making them ideal for adding volume, colour, and flavour to meals without meaningfully increasing the overall calorie count.
Are tomatoes a Free Food on Slimming World?
Yes — fresh, tinned, and passata tomatoes are all Free Foods and Speed Foods on Slimming World. You can eat them without counting Syns in any quantity. This applies to raw tomatoes in salads, tinned tomatoes in sauces and soups, and passata as a cooking base. Sundried tomatoes in oil are not Free, as they are calorically concentrated and the oil adds significant fat. Sun-dried tomatoes preserved in brine are lower in calories but still check the current SW app for their Syn value.
Are cooked tomatoes more nutritious than raw?
For lycopene content, yes — cooked tomatoes are more nutritious. Heat breaks down the tomato's cell walls and transforms lycopene into a form your body can absorb more readily. Studies show that eating tomatoes cooked in a small amount of fat can increase lycopene absorption by up to four times compared to raw. For vitamin C, the reverse is true — cooking destroys some vitamin C, so raw tomatoes have the edge there. For overall nutrition, a combination of both raw and cooked tomatoes is ideal.
Can I eat tinned tomatoes freely on Slimming World?
Yes — plain tinned tomatoes (whole, chopped, or plum) are Free Foods on Slimming World. They are one of the most useful store-cupboard Free Foods, forming the base of countless syn-free pasta sauces, soups, curries, and stews. A standard 400g tin of chopped tomatoes contains around 72 calories in total, making it calorie-negligible as a sauce base. Check the label to ensure the only ingredients are tomatoes and tomato juice — some flavoured varieties contain added salt, sugar, or herbs, but these are still generally Free.
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