Onion vs. Tomato

Nutrition comparison of Onion and Tomato


Ever wonder how your favorite foods stack up against each other in terms of nutrition?

We compared the nutritional contents of onion versus tomato (100g each) below using 2020 USDA and NIH data[1].

For a quick recap of significant nutrients and differences in onion and tomato:

  • Tomato has 55% less calories than onion.
  • Tomato has more niacin.
  • Tomato is a great source of Vitamin C and potassium.
Detailed nutritional comparison of onion and tomato is analyzed below. You can also visualize the nutritional comparison for a custom portion or serving size and see how the nutrition compares.

USDA sources for nutritional information: Onion (Onions, raw) and Tomato (Tomatoes, red, ripe, raw, year round average) . Have a correction or suggestions? Shoot us an email.


Image of Onion src
Image of Tomato src

Calories and Carbs

calories

Tomato has 55% less calories than onion - onion has 40 calories per 100 grams and tomato has 18 calories.

For macronutrient ratios, onion is lighter in protein, heavier in carbs and lighter in fat compared to tomato per calorie. Onion has a macronutrient ratio of 10:88:2 and for tomato, 17:74:9 for protein, carbohydrates and fat from calories.

Macro Ratios from Calories:

Onion Tomato
Protein 10% 17%
Carbohydrates 88% 74%
Fat 2% 9%
Alcohol ~ ~

carbohydrates

Onion and tomato contain similar amounts of carbs - onion has 9.3g of total carbs per 100 grams and tomato has 3.9g of carbohydrates.

dietary fiber

Onion has 42% more dietary fiber than tomato - onion has 1.7g of dietary fiber per 100 grams and tomato has 1.2g of dietary fiber.

sugar

Onion and tomato contain similar amounts of sugar - onion has 4.2g of sugar per 100 grams and tomato has 2.6g of sugar.

Protein

protein

Onion and tomato contain similar amounts of protein - onion has 1.1g of protein per 100 grams and tomato has 0.88g of protein.

Fat

saturated fat

Both onion and tomato are low in saturated fat - onion has 0.04g of saturated fat per 100 grams and tomato has 0.03g of saturated fat.

Vitamins

Vitamin C

Tomato is a great source of Vitamin C and it has 85% more Vitamin C than onion - onion has 7.4mg of Vitamin C per 100 grams and tomato has 13.7mg of Vitamin C.

Vitamin A

Tomato has more Vitamin A than onion - tomato has 42ug of Vitamin A per 100 grams and onion does not contain significant amounts.

Vitamin E

Onion and tomato contain similar amounts of Vitamin E - onion has 0.02mg of Vitamin E per 100 grams and tomato has 0.54mg of Vitamin E.

Vitamin K

Onion and tomato contain similar amounts of Vitamin K - onion has 0.4ug of Vitamin K per 100 grams and tomato has 7.9ug of Vitamin K.

The B Vitamins

Tomato has more niacin. Both onion and tomato contain significant amounts of thiamin, riboflavin, pantothenic acid, Vitamin B6 and folate.

Onion Tomato
Thiamin 0.046 MG 0.037 MG
Riboflavin 0.027 MG 0.019 MG
Niacin 0.116 MG 0.594 MG
Pantothenic acid 0.123 MG 0.089 MG
Vitamin B6 0.12 MG 0.08 MG
Folate 19 UG 15 UG

Minerals

calcium

Onion has 130% more calcium than tomato - onion has 23mg of calcium per 100 grams and tomato has 10mg of calcium.

iron

Onion and tomato contain similar amounts of iron - onion has 0.21mg of iron per 100 grams and tomato has 0.27mg of iron.

potassium

Tomato is a great source of potassium and it has 62% more potassium than onion - onion has 146mg of potassium per 100 grams and tomato has 237mg of potassium.

Antioxidants and Phytonutrients

flavonoids

Naturally occuring in fruits and vegetables, flavonoids are associated with many health benefits and used in a variety of medicinal and pharmaceutical applications. [2][3]

For specific flavonoid compounds, both onion and tomato contain small amounts of myricetin.

Onion Tomato
apigenin 0.01 mg ~
luteolin 0.02 mg ~
isorhamnetin 5.01 mg ~
kaempferol 0.65 mg 0.09 mg
myricetin 0.03 mg 0.13 mg
Quercetin 20.3 mg 0.58 mg

carotenoids

Carotenoids are micronutrients commonly found in plants and some animal products. An example is beta-carotene, the notable carotenoid which is a popular source of Vitamin A.[4][5]

For specific types of carotenoids,

Onion Tomato
beta-carotene 1 UG 449 UG
lutein + zeaxanthin 4 UG 123 UG
alpha-carotene ~ 101 UG
lycopene ~ 2573 UG

Omega-3 and Omega-6

omega 3s

For omega-3 fatty acids, both onion and tomato contain small amounts of alpha linoleic acid (ALA).

Onion Tomato
alpha linoleic acid 0.004 G 0.003 G
Total 0.004 G 0.003 G

omega 6s

Comparing omega-6 fatty acids, tomato has more linoleic acid than onion per 100 grams.

Onion Tomato
linoleic acid 0.013 G 0.08 G
Total 0.013 G 0.08 G



Customize your serving size


The comparison below is by weight, but sometimes 100g isn't that intuitive of a measurement for food. View a custom portion comparison (e.g. cups, oz, package).

You can try adding or subtracting the amount of either Onion or Tomato .

Note: The specific food items compared are: Onion (Onions, raw) and Tomato (Tomatoes, red, ripe, raw, year round average) .

Onion g

()
Daily Values (%)

Tomato g

()
KCAL %
calories
KCAL %
G %
carbohydrates
G %
G %
dietary fiber
G %
G sugar G
G %
total fat
G %
G %
saturated fat
G %
G monounsaturated fat G
G polyunsaturated fat G
G trans fat G
MG cholesterol MG
MG %
sodium
MG %
Vitamins and Minerals
UG %
Vitamin A
UG %
MG %
Vitamin C
MG %
IU %
Vitamin D
IU %
MG %
calcium
MG %
MG %
iron
MG %
MG %
magnesium
MG %
MG %
potassium
MG %
MG %
thiamin (Vit B1)
MG %
MG %
riboflavin (Vit B2)
MG %
MG %
niacin (Vit B3)
MG %
MG %
Vitamin B6
MG %
MG %
pantothenic acid (Vit B5)
MG %
UG %
folate (Vit B9)
UG %
UG %
Vitamin B12
UG %
MG %
Vitamin E
MG %
UG %
Vitamin K
UG %
G %
protein
G %
UG %
biotin (Vit B7)
UG %
MG %
choline
MG %
MG %
chlorine
MG %
UG %
chromium
UG %
MG %
copper
MG %
UG %
fluoride
UG %
UG %
iodine
UG %
MG %
manganese
MG %
UG %
molybdenum
UG %
MG %
phosphorus
MG %
UG %
selenium
UG %
MG %
zinc
MG %
G Water G
G Starch G
G Alcohol G


FAQ

Does onion or tomato contain more calories in 100 grams?
Tomato has 60% less calories than onion - onion has 40 calories in 100g and tomato has 18 calories.

Does onion or tomato have more carbohydrates?
By weight, onion and tomato contain similar amounts of carbs - onion has 9.3g of carbs for 100g and tomato has 3.9g of carbohydrates.