Are Tomatoes Keto-Friendly? Carbs in Tomatoes Explained

Yes — tomatoes are keto-friendly in normal portions. Raw tomatoes have only about 2.7g net carbs per 100g, and a medium tomato is roughly 3g net carbs, so they fit easily into a daily keto budget of 20-50g. The catch is processed tomato products — ketchup, sweetened pasta sauces, tomato paste, and sun-dried tomatoes pack far more carbs per serving.

Tomatoes get a bad rap on keto because they're botanically a fruit, and fruit usually means sugar. But tomatoes are one of the lowest-sugar "fruits" you can eat. The bigger trap isn't the tomato itself — it's what people do to it. Below is exactly where tomatoes land on keto, and which forms to watch.

Tomato carbs by form

Net carbs = total carbs minus fiber. These are typical values; you can log any of them in CarbMeNot to get exact numbers for your portion.

Tomato form	Net carbs (per serving)	Keto-friendly?
Raw tomato	~2.7g per 100g	Yes
Medium tomato	~3.3g each	Yes
Cherry tomatoes	~2.8g per 100g (~0.5g each)	Yes
Canned diced/whole tomatoes	~3g per 100g	Yes
Tomato sauce / passata (plain)	~4g per ½ cup	Yes
Tomato paste	~6g per 2 tbsp	In moderation
Jarred pasta / marinara sauce	~6-10g per ½ cup	Check the label
Ketchup	~4g per tablespoon	In moderation
Sun-dried tomatoes	~6g per ¼ cup (oil-packed)	In moderation

Are tomatoes keto?

Yes, comfortably. A keto diet generally caps you at 20-50g of net carbs per day, and a single medium tomato uses only about 3g of that. Even a generous serving of sliced tomato on a salad or burger barely moves the needle.

What makes tomatoes work is their water and fiber content. They're roughly 95% water, which dilutes the sugar per gram, and the fiber you subtract to get net carbs further lowers the count. Compared to other "fruits," tomatoes are firmly in keto-friendly territory alongside the lowest-carb vegetables.

They also bring nutrients worth having: vitamin C, potassium (useful when you're managing keto electrolytes), and lycopene, the antioxidant that gives tomatoes their red color.

How many carbs are in tomatoes?

Here's the breakdown for raw tomatoes:

• Per 100g (about 3.5 oz): ~3.9g total carbs, ~1.2g fiber, ~2.7g net carbs
• One medium tomato (~120g): ~3.3g net carbs
• One cherry tomato (~17g): ~0.5g net carbs
• One cup chopped (~180g): ~4.8g net carbs

So you'd need to eat roughly seven medium tomatoes to hit 20g of net carbs from tomatoes alone — far more than anyone eats in a sitting. For full nutrition details, see the tomato carbs page.

Cherry and grape tomatoes are essentially the same per gram, which makes them an easy keto snack. A handful is a couple of grams of net carbs, tops.

Tomato products to watch

This is where keto dieters get caught. Concentrating or sweetening tomatoes multiplies the carbs:

• Ketchup — around 4g net carbs per tablespoon, and most of it is added sugar. Two or three squeezes adds up fast. Look for no-sugar-added versions.
• Jarred pasta and marinara sauces — many brands add sugar, pushing them to 6-10g net carbs per half cup. Plain canned tomatoes or passata are the safer base.
• Tomato paste — concentrated, so about 6g net carbs per 2 tablespoons. Fine in small amounts to deepen flavor, but easy to overdo.
• Sun-dried tomatoes — drying removes water and concentrates the sugar, landing around 6g net carbs per quarter cup. Use them as an accent, not a handful.
• Tomato soup and tomato juice — frequently sweetened; check the label before assuming they're low-carb.

The pattern is simple: the more processed and concentrated the tomato, the more carbs per bite. Whole and minimally processed tomatoes are your friend.

How to enjoy tomatoes on keto

Tomatoes are one of the most versatile keto ingredients once you sidestep the sugary products:

• Slice fresh tomatoes onto burgers, salads, and lettuce wraps
• Snack on cherry tomatoes with cubes of cheese or a drizzle of olive oil
• Make a quick sauce from plain canned tomatoes, garlic, olive oil, and herbs — no added sugar
• Build a caprese with fresh mozzarella, basil, and a splash of balsamic
• Roast tomatoes to concentrate flavor without adding carbs
• Blend a fresh gazpacho or homemade salsa, skipping any sugar the recipe calls for

When you cook with tomatoes, the smartest move is to control the sauce yourself so you know exactly what's in it. Log the raw ingredients in CarbMeNot and you'll see your real net carbs instead of guessing from a jar.

Know the carbs before you bite

Tomatoes are keto-friendly, but the difference between a fresh tomato and two tablespoons of ketchup is the difference between 3g and 8g of net carbs. CarbMeNot uses AI-powered food recognition to scan a meal or a label and break down net carbs instantly, so you always know whether something fits your day. Browse the vegetables database to check any ingredient, and let CarbMeNot keep your running total honest. Download CarbMeNot and track your carbs the easy way.

Key takeaways

• Tomatoes are keto-friendly at about 2.7g net carbs per 100g, or ~3g for a medium tomato.
• You can comfortably eat 2-3 tomatoes a day and stay well within a 20-50g net carb budget.
• Cherry and canned tomatoes are just as keto-safe as fresh ones.
• Watch processed products — ketchup (~4g/tbsp), sweetened pasta sauce (6-10g/½ cup), tomato paste, and sun-dried tomatoes carry far more carbs.
• Make sauces from plain tomatoes and log them in CarbMeNot to keep your net carbs accurate.