The reference tomato record
USDA SR Legacy 2018 gives 11.0 mg magnesium per 100 g for raw red ripe tomatoes, using a year-round average. Its 123 g medium whole tomato provides about 13.5 mg. A 180 g cup of chopped or sliced tomato gives 19.8 mg. These values describe food content rather than absorption. [1]
A tomato slice is not a whole tomato
The same record lists a medium slice at 20 g, giving only 2.2 mg magnesium. A count such as one slice or one cup is useful only with its portion definition. Tomato paste, sauce, juice and dried tomatoes have different compositions and should not inherit the raw-tomato value. [1]
A hypothetical salad calculation
For a salad containing 150 g raw tomato, multiply 11 mg by 1.5 to obtain 16.5 mg magnesium. A 300 g tomato portion doubles that estimate to 33.0 mg. Additional salad ingredients contribute separately; the calculation does not identify a treatment for magnesium deficiency. [1]
| Tomato amount | Estimated magnesium |
|---|---|
| 150 g | 16.5 mg |
| 300 g | 33.0 mg |
Sources for this article
- USDA FoodData Central — SR Legacy April 2018 food composition dataset
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.