One cup of cooked black beans provides about 120 mg of magnesium, based on USDA data.
Chasing a dependable, everyday source of magnesium? A simple bowl of black beans does the job. The cup you add to a burrito bowl or stir into chili brings a solid dose of this mineral along with fiber, protein, and folate. Below you’ll find clear numbers, smart ways to measure a “cup,” and easy tips to keep the count consistent in your kitchen.
What You Get Per Cup
A typical 1 cup cooked serving lands around 120 mg of magnesium and roughly 15 grams each of protein and fiber. The same serving usually includes over 600 mg of potassium, plus a generous hit of folate. That mix turns black beans into a practical base for bowls, soups, tacos, and salads while nudging your daily magnesium intake in the right direction.
Black Bean Portions And Magnesium
| Serving | Magnesium (mg) | % DV (420 mg) |
|---|---|---|
| 1/2 cup cooked | 60 | 14% |
| 1 cup cooked | 120 | 29% |
| 1 cup canned, drained | ~90 | 21% |
Notes: Values reflect common lab summaries for cooked beans. Canned amounts vary by brand, packing liquid, and how well beans are rinsed.
Magnesium In One Cup Of Black Beans: Cooked Vs. Canned
Cooked From Dry
Soaked and simmered beans hold less free liquid per cup than canned. That tighter cup means more minerals per scoop. Expect about 120 mg of magnesium in a level 1 cup cooked serving.
Canned And Drained
Convenience wins on busy nights. A drained cup often lands a bit lower, commonly near the 80–95 mg range. The difference comes from added water in the can and slight serving-weight shifts. If the Nutrition Facts panel lists magnesium, trust that number for the brand in your pantry.
Does Rinsing Change The Count?
A brisk rinse cuts sodium and surface starch. Magnesium sits inside the seed, so a quick rinse doesn’t move the needle in a meaningful way.
How These Numbers Are Established
Large nutrient databases compile lab analyses and assign standard household measures. For cooked black beans, one cup is typically set at about 172 grams, and that serving shows ~120 mg of magnesium with roughly 29% Daily Value. You can review the exact entry in USDA-linked nutrition data, which also displays the serving mass used and the full mineral list.
How A Cup Fits Your Day
Adults need a few hundred milligrams of magnesium each day. A single cooked cup of black beans covers close to a third of the label Daily Value, and an even bigger share of many women’s targets. For reference, the magnesium fact sheet lists adult RDAs of 400–420 mg for most men and 310–320 mg for most women.
Adult Targets And What One Cup Delivers
| Group | Target (mg/day) | % From 1 Cup Cooked* |
|---|---|---|
| Men 19–51+ | 400–420 | ~29–30% |
| Women 19–51+ | 310–320 | ~38–39% |
| Pregnancy | 350–360 | ~33–34% |
*Based on 120 mg per cooked cup.
What Counts As “A Cup”
Databases tie household cups to a fixed weight to keep numbers consistent. For cooked black beans that’s commonly ~172 g. A tightly packed scoop can weigh a bit more; a looser scoop with extra broth can weigh a bit less. That small swing explains why two sources might disagree by a few milligrams while still pointing to the same ballpark.
Other Nutrients You Get In That Same Bowl
Fiber
About 15 grams per cooked cup. That helps with regularity and keeps meals satisfying without a heavy calorie load.
Protein
Roughly 15 grams per cup. Pair with grains to round out amino acids in vegetarian meals.
Folate And Potassium
Black beans supply a strong dose of folate and more than 600 mg of potassium per cup. That pairing supports cell growth and helps balance sodium in rice-and-bean dinners, tacos, and stews.
Cooking Choices That Influence Magnesium Per Serving
Soaking
Overnight soaking trims cook time and can yield a creamy texture. Minerals remain inside the beans, so draining the soak water doesn’t meaningfully cut magnesium.
Salt And Acids
Season once skins have softened to keep the pot tender. Tomato, citrus, or vinegar keep skins intact; add near the end for even cooking. These tweaks change texture more than mineral numbers.
Boil Or Pressure Cook
Both methods produce similar mineral counts per cooked cup. Pressure cookers shine when you want dry beans ready in under an hour.
Storage
Cool cooked beans in their broth. Refrigerate up to four days or freeze for a month. Reheating doesn’t erase the magnesium in your portion.
Label Reading Tips
If your can lists magnesium, use that figure. Brands may pack beans in different liquids or list slightly different serving weights. When magnesium isn’t listed, use serving mass as a clue. A half-cup labeled at 130 g suggests a looser pack than a home-cooked half-cup around 86 g, which helps explain smaller numbers on some labels.
Who Benefits Most From Bean-Based Magnesium
People who avoid dairy, anyone on budget-friendly eating plans, and athletes who sweat a lot tend to benefit from steady legume intake. Two meals that each include a cup of beans can cover a big share of daily magnesium while boosting fiber and plant protein.
Possible Gut Reactions And Easy Fixes
Beans contain fermentable carbs that can feel gassy when intake jumps. Increase portions gradually, sip water with meals, and season with cumin, oregano, or garlic. Pressure-cooked beans and a good rinse on canned beans can help sensitive eaters.
Allergy And Safety Notes
True allergies to black beans are uncommon, but they do exist. People with known legume allergies should follow medical guidance. For infants and small kids, mash beans to a soft texture. With canned beans, check dates, refrigerate leftovers in food-safe containers, and reheat to steaming.
How To Measure A Cup Without A Scale
Use a standard measuring cup and level the top. If beans are saucy, drain briefly so the measure reflects solids more than broth. For repeatable results, weigh a cooked serving once, see how it fills your favorite bowl, and use that visual cue as your everyday guide.
Quick Answers To Common Measurement Questions
Dried To Cooked Yield
One cup of dry beans makes about three cups cooked. The mineral count is reported per cooked cup, so the ~120 mg figure still applies to each 1 cup portion you serve.
Soups And Stews
In brothy dishes a “cup” can include lots of liquid. Magnesium follows the beans themselves. If your ladle holds more broth than beans, the count per cup skews lower simply because there’s less bean in the scoop.
Restaurant Sides
Side portions vary. If the ramekin looks like half a cup, pencil in about 60 mg. A generous side closer to a full cup will sit near 120 mg when beans are cooked and drained.
Simple Black Bean Prep You Can Trust
1) Quick Soak
Cover dry beans with water by a few inches, bring to a brief boil, rest one hour, then drain.
2) Cook
Add fresh water, a bay leaf, and onion. Simmer gently until tender, skimming foam as needed.
3) Season
Add salt after skins soften. Finish with lime or a splash of vinegar right before serving.
4) Store
Cool in cooking liquid. Refrigerate up to four days or freeze in portions for fast meals.
When A Supplement Comes Up
Food should lead. If a clinician suggests a supplement, check the label for elemental magnesium and common forms like citrate, glycinate, or oxide. Small amounts with meals tend to sit well for most people. Laxative products can contain very large doses that are not intended for daily nutrition.
Bottom Line
One full cup of cooked black beans supplies about 120 mg of magnesium, close to a third of the Daily Value. Keep a couple of cans in the pantry and a batch of cooked beans in the fridge, and you’ll have a reliable way to meet your target day after day while adding fiber, protein, and flavor to your plate.