One medium banana (118 g) packs about 32 mg of magnesium; smaller fruit lands near 27 mg and a large one about 37 mg.
Wondering how many milligrams of magnesium you get from a banana? You’ll find a steady, predictable range tied to the weight of the edible portion. A medium fruit sits around the low-30s in milligrams, which makes bananas a handy, everyday source that fits breakfast bowls, snacks, and post-workout shakes without any fuss.
How Many Milligrams Of Magnesium Are In Bananas?
Magnesium in bananas tracks closely with size. Per 100 grams of edible fruit, bananas average about 27 mg of magnesium. That baseline lets you estimate any common serving with simple math. A small banana (about 101 g) delivers near the high-20s. A medium (about 118 g) lands around 32 mg. A large (about 136 g) moves up to the high-30s. Cup-based measures behave the same way: a cup of sliced banana (roughly 150 g) sits near 41 mg. These figures come from nutrient datasets used by dietitians and food labels and mirror what you’ll see on widely used nutrition tools that source the USDA.
Magnesium By Portion: Banana Cheat Sheet
The table below pulls together the typical range you’ll see for common sizes. Use it to ballpark your intake without a scale.
| Portion | Magnesium (mg) | Typical Weight (g) |
|---|---|---|
| Per 100 g (raw) | 27 | 100 |
| Small banana | ~27 | 101 |
| Medium banana | ~32 | 118 |
| Large banana | ~37 | 136 |
| 1 cup sliced | ~41 | 150 |
Why the wiggle room? Whole fruit grows in different lengths and girths, so two “medium” bananas can weigh a bit differently. The nutrient profile stays steady per 100 g; the final number you eat rides on weight.
How This Compares To Your Daily Needs
Daily magnesium needs vary by age and sex. Adult targets fall in the low-to-mid 300s for many women and around the low-400s for many men. One medium banana gives a modest slice of that target, and it pairs well with higher-magnesium foods like pumpkin seeds, almonds, black beans, and leafy greens.
What A Banana Contributes Toward The Day
Here’s the simple math for a medium banana at ~32 mg. If your target is around 320 mg, one banana supplies about a tenth of the day. If your target is around 420 mg, it supplies just under that. That’s solid for a fruit that’s portable, sweet, and easy on the stomach.
Does Ripeness Change The Magnesium Number?
Ripeness shifts texture and the ratio of starch to sugars. It doesn’t swing the mineral totals much in either direction. The main driver is still portion weight. Whether you like yours freckled or firm, the per-gram mineral content remains consistent enough that a scale and the 27-mg-per-100-g baseline can guide you.
Other Nutrients You Grab With That Banana
Magnesium isn’t the only win. A medium banana brings potassium in the low-400-mg range, plus about 3 g of fiber and a bump of vitamin B6. That combo supports fluid balance, regularity, and everyday energy metabolism. If you’re reaching for a fast snack after a sweaty session, the mix of carbohydrates, potassium, and magnesium makes bananas an easy add-on.
Smart Ways To Hit Your Magnesium Target
Bananas help, but you’ll likely need more than one source to reach the day’s total. Mix and match from nuts, seeds, legumes, whole grains, and greens. Here are practical pairings that fit busy routines:
Grab-And-Go Ideas
- Banana with a small handful of pumpkin seeds.
- Overnight oats with sliced banana and chopped almonds.
- Yogurt parfait with banana coins and chia.
Meal Ideas
- Spinach omelet with banana on the side.
- Brown rice bowl with black beans, avocado, and banana for dessert.
- Whole-grain toast with peanut butter and banana slices.
For full context on daily needs by age and life stage, see the NIH’s magnesium fact sheet, which lists current RDAs used by clinicians and dietitians. You can scan the detailed table there to match your target to your age and life stage. To check banana numbers by serving size, a widely used nutrition database built on USDA data shows per-100-g and per-portion magnesium values, which you can toggle to match your banana size. For convenience, this page includes both links in one place mid-scroll, right where most readers want them:
Portion Math You Can Use Anywhere
Once you learn the 27-mg-per-100-g rule of thumb, the rest is easy. Here’s a quick walk-through you can apply to any banana on your counter:
- Pick your portion. Whole fruit by length works fine, but weight is even better.
- Estimate or weigh. If you don’t have a scale, use the small/medium/large ranges in the first table.
- Multiply. Take the weight in grams and use the 27-mg-per-100-g baseline to estimate magnesium.
Example: a 130-g banana × 0.27 mg per gram lands near 35 mg magnesium. That’s fast, and it stays consistent across varieties you’ll see in stores.
How Bananas Stack Up Against Other Foods
Bananas are a steady contributor, but some foods sit far higher per bite. Seeds and nuts often lead the pack. Legumes and greens add helpful amounts too. Building plates that mix a banana with one or two of these choices lifts your total without menu stress.
Pair Bananas With Higher-Magnesium Staples
- Pumpkin seeds: compact, easy to sprinkle on oats or yogurt.
- Almonds or cashews: snack cups or trail mix.
- Black beans: burrito bowls, soups, or quick canned add-ins.
- Cooked spinach or chard: sautés and omelets.
- Whole grains: oats, quinoa, and whole-wheat pasta.
Banana Size Guide: How Stores Label Lengths
Most produce guides treat “small” as near 6 inches, “medium” near 7–7⅞ inches, and “large” near 8–8⅞ inches. These bands line up with the gram weights in the first table. If your fruit looks a touch bigger or smaller than the estimates, your magnesium number will shift a hair, but it’ll still sit in the ranges shown.
Daily Needs Table And What One Banana Covers
Use this table to match your daily target and see how a single medium banana (~32 mg) moves the needle.
| Group | RDA (mg/day) | % From One Medium Banana |
|---|---|---|
| Men 31+ y | 420 | ~8% |
| Men 19–30 y | 400 | ~8% |
| Women 31+ y | 320 | ~10% |
| Women 19–30 y | 310 | ~10% |
| Teens 14–18 y (M) | 410 | ~8% |
| Teens 14–18 y (F) | 360 | ~9% |
| Kids 9–13 y | 240 | ~13% |
| Pregnancy 19–30 y | 350 | ~9% |
| Pregnancy 31–50 y | 360 | ~9% |
| Lactation 19–30 y | 310 | ~10% |
| Lactation 31–50 y | 320 | ~10% |
Banana Picks For Different Goals
For A Quick Snack
Grab a medium fruit and pair it with a nut or seed source. You’ll nudge magnesium, add protein and fiber, and stay satisfied longer.
For A Breakfast Bowl
Slice a banana over oats, add a spoon of nut butter, and finish with a sprinkle of seeds. You’ll boost magnesium without leaning on supplements.
For Post-Workout Fuel
Blend a banana with milk or a non-dairy alternative and a spoon of yogurt. The mix brings carbs, potassium, and a steady shot of magnesium to round out recovery.
Buying, Storing, And Prepping For Best Texture
Pick fruit with bright yellow peel if you like a softer bite and more sweetness; lean greener if you prefer a firmer chew. Store at room temp for ripening and move to the fridge to slow it down. Chill may darken the peel, but the inside stays fine. For smoothies, peel and freeze ripe bananas in chunks to cut prep time and waste.
Key Takeaways You Can Act On Today
- Count on ~27 mg of magnesium per 100 g of banana.
- One medium fruit (~118 g) gives about 32 mg; a large (~136 g) sits near 37 mg.
- Match your daily target by mixing a banana with nuts, seeds, beans, grains, and greens.
- Use the portion tables above to estimate quickly without a scale.
Method Notes And Data Sources
Numbers in this guide rely on per-100-g nutrient values applied to common banana weights and cup measures. The daily targets reflect widely used reference values published by national health agencies. Linked resources mid-article show the detailed nutrient tables and the full RDA chart used by clinicians.