How Much Magnesium Is in Tomatoes? Per 100 g and Common Servings

Raw red tomatoes provide about 11 mg per 100 g, roughly 16 mg in one medium tomato weighing 149 g, and about 24 mg in one cup of chopped tomato. These values give you a practical baseline for comparing fresh tomatoes, canned tomatoes, and other products by serving size.

For you, the useful comparison depends on edible weight, drained weight, water content, and added ingredients. The guidance below helps you interpret labels and build a magnesium-conscious meal.

Raw Red Tomato Magnesium Values

Each 100-gram portion of raw red tomato supplies approximately 11 mg of magnesium. That baseline comes from USDA FoodData Central and lets you compare fresh portions with canned, cooked, or concentrated products.

One cup of chopped red tomato weighs about 240 g in USDA portion data and supplies roughly 24 mg of magnesium. Your cup can weigh less or more because chopping changes packing density, so grams provide the most consistent basis.

Matching magnesium to portion size

Weight gives you a more reliable comparison than the word “serving.” A medium tomato varies with diameter and water content, while a cup of chopped tomatoes can hold different quantities depending on how tightly the pieces are packed.

Your estimate changes with the cut mainly because the amount of edible fruit changes. A heaped cup weighs more than a tightly packed cup, and one wedge can weigh less than a large slice from the same tomato.

Accounting for skin, seeds, and cores

Tomato skin, seeds, and core contribute to the edible weight, although ordinary nutrition entries usually report the combined fruit without separating those plant parts. Draining canned tomatoes removes liquid rather than removing most of the magnesium held in the tomato solids.

Sliced and diced tomatoes do not have separate, fixed nutrient totals. Their magnesium content comes from the fruit and the serving weight you eat, so weighing 100 g of either form produces a more comparable estimate.

How Tomato Magnesium Fits Your Daily Needs

The Daily Value for magnesium on U.S. Nutrition Facts labels is 420 mg for adults. Your personal needs can differ because age, sex, pregnancy status, health, medication use, and the rest of your diet affect how much magnesium you need.

A 100-gram serving provides about 3% of the 420 mg Daily Value. One medium tomato supplies about 4%, while a 240-gram cup of raw pieces provides about 6%, making tomatoes a supporting food rather than a primary magnesium source.

Comparing servings with the Daily Value

Your remaining intake does not have to come from one food. Beans, whole grains, nuts, seeds, leafy greens, and fortified foods can supply the balance, while your meal pattern determines whether those choices fit your needs.

Magnesium supports hundreds of enzyme systems involved in nerve function, muscle contraction, and glucose metabolism. Pumpkin seeds, almonds, black beans, oats, and spinach contribute more per typical serving, which aligns with guidance from the National Institutes of Health Office of Dietary Supplements.

Fresh and Canned Tomato Comparisons

Fresh and canned tomatoes can have similar magnesium values when you compare equal drained or edible weights. A canned can includes liquid, so its total listed weight does not represent the same amount of tomato solids as a fresh-tomato weight.

Comparing common tomato forms

Your canned-tomato comparison starts with the drained weight rather than the total can weight. A can may list the weight of its contents plus liquid, while the tomato solids account for only part of that measurement.

Ingredient lists matter because tomato juice, sugar, oil, and salt change what you consume with the fruit. A product containing several tomatoes may still provide only a small amount of magnesium after you account for its actual drained weight.

Evaluating sauce, juice, and paste

Comparing labels and nutrient data reveals substantial variation in the magnesium content of tomato products. Tomato juice contains a substantial amount of water, while sauce and paste lose water during concentration, making their mineral density per tablespoon higher.

Tomato paste may look magnesium-dense because it contains less water. Cooking doesn’t create magnesium; the mineral was already present in the starting tomatoes, and water removal makes the same amount appear larger in a smaller serving.

Raw and Cooked Tomato Content

Raw and cooked tomatoes contain similar total magnesium before you account for weight changes. Steaming, roasting, boiling, and simmering can remove water, so a smaller serving of cooked tomato can appear more concentrated.

Following water loss through cooking

Suppose you begin with 250 g of chopped tomato and simmer it until the finished mixture weighs 175 g. Its magnesium remains close to the original total, apart from losses during cooking and handling, because the water carries no magnesium.

Your concentration rises because the same amount of magnesium occupies a smaller final weight. Dividing 27.5 mg by 100 g gives about 11 mg per 100 g before cooking, while 27.5 mg in 175 g equals about 15.7 mg per 100 g afterward.

You should match your calculation to the weight used by the source. Multiplying a USDA value stated per 100 g by cooked weight works mathematically, but a household cup cannot replace grams unless you account for changed density.

Separating concentration from total intake

Raw tomato nutrition facts describe the edible fruit before water loss. Cooked values depend on the recipe and final weight, so two cups of cooked pieces do not necessarily match two cups of raw pieces in either mass or magnesium.

Your total amount consumed matters more than concentration alone. You might eat a tablespoon of concentrated paste or several cups of watery juice, and the serving size changes the relationship between density and actual intake.

Variety, Ripeness, and Plant Parts

Tomato variety, ripening, soil, climate, and plant part can cause modest differences in nutrient composition. Standard consumer tables rarely separate magnesium by cultivar, leaving the ordinary red-tomato value as a practical estimate.

Recognizing limitations in standard values

Green portions and tomato leaves differ nutritionally from ripe red flesh. You shouldn’t assume that a leaf, specialty cultivar, or concentrated powder follows the standard red-tomato figure, especially when your serving is very small.

Skin and seeds count as part of the edible fruit, but their separate contributions are rarely listed in standard entries. Your estimate stays more dependable when you use an average value and recognize that cultivar and ripeness can shift the result slightly.

Ripening can also change the composition of an individual tomato as its color, water content, and sugars develop. A label for one commercial variety may not describe a homegrown tomato with a different size and growing environment.

“Use the raw red tomato baseline of 11 mg per 100 g, then adjust for drained weight, water loss, added ingredients, and the amount you actually eat.

Label Calculations for Accurate Estimates

You calculate a labeled Daily Value percentage by dividing the declared magnesium by 420 mg and multiplying by 100. A product listing 10 mg per serving provides about 2.4%, normally rounded to 2% on a Nutrition Facts panel.

For a product without a magnesium declaration, first identify the edible or drained tomato weight. Apply the 11 mg per 100 g benchmark, subtract the effects of other ingredients when necessary, and compare that estimate with your portion.

Following a practical calculation checklist

• ▸Check the serving size. Use grams or ounces before relying on a household cup measure.
• ▸Separate drained weight. For canned tomatoes, use the solid tomato amount rather than the full can weight.
• ▸Read the ingredient list. Tomato juice, oil, sugar, and salt change the context of your serving.
• ▸Convert to Daily Value. Divide magnesium milligrams by 0.420 to get the adult U.S. label percentage.
• ▸Count each form once. Don’t count sauce, canned tomatoes, and tomato juice separately when they come from the same dish.

Your meal can combine 24 mg from tomatoes with black beans, brown rice, oats, nuts, seeds, or leafy greens. Those additions raise the meal’s magnesium content more substantially than increasing the tomato portion alone.

Treat a published estimate as a planning number rather than a laboratory measurement. Variety, crop conditions, recipe changes, and portion differences create uncertainty, while a Nutrition Facts panel provides the most specific value for a commercial product.

Using the label value with an accurate serving size makes tomatoes easier to place within a magnesium-rich eating pattern.

Building a Magnesium-Rich Diet Around Tomatoes

A full serving of tomatoes contributes several percent of the adult Daily Value, although the fruit is not among the richest magnesium sources. Pairing it with beans, seeds, nuts, or whole grains makes your plate a stronger source.

Choosing complementary dietary sources

• ▸Nuts and seeds: Pumpkin seeds, almonds, and cashews supply more magnesium per serving than tomatoes.
• ▸Legumes: Black beans, chickpeas, lentils, and soybeans add magnesium along with fiber and protein.
• ▸Whole grains: Oats, brown rice, and whole wheat contribute magnesium based on the amount you eat.
• ▸Leafy greens: Spinach and similar greens add dietary minerals, although preparation changes the serving weight.
• ▸Fortified foods: Certain cereals and plant-based drinks supply added magnesium, so the label gives the amount.

You can make tomato and black bean salad or serve tomato sauce over whole-grain pasta with beans. Chopped tomatoes also work alongside spinach, almonds, and pumpkin seeds when you want a meal that combines produce with larger magnesium sources.

Your body doesn’t absorb magnesium from every food equally. Fiber, phytates, and some meal combinations can affect absorption, so your total nutrition cannot be inferred from one tomato serving or one isolated mineral number.

Those absorption differences are why individual health needs and medication considerations should shape any dietary advice.

Individualized Guidance for Specific Needs

Your magnesium needs can change during pregnancy, aging, illness, or medication changes. With a diagnosed deficiency, restrictive eating pattern, kidney disease, or specific nutrient needs, you need guidance beyond a single tomato estimate.

A registered dietitian or qualified clinician can assess your total intake and health context. That individualized approach matters because the 420 mg Daily Value is a labeling reference, not a universal treatment target for every adult.

Bottom Line

Raw red tomatoes provide about 11 mg of magnesium per 100 g, 16 mg in a medium tomato, and 24 mg in a cup of raw pieces. You can count them as a supporting food, while legumes, seeds, nuts, whole grains, leafy greens, and fortified products help build a magnesium-rich diet.

FAQ