A medium baked sweet potato (about 5 inches long) contains roughly 542 milligrams of potassium. That’s about 12% of the 4,700 mg daily value recommended for adults, making sweet potatoes one of the more potassium-dense foods you can eat.
Potassium by Preparation Method
How you cook a sweet potato significantly affects how much potassium ends up on your plate. Baking, roasting, or microwaving preserves the most potassium because the mineral stays locked inside the flesh. Boiling is a different story: cutting potatoes into cubes before boiling reduces potassium by about 50%, and shredding them before boiling drops it by as much as 75%. The potassium leaches into the cooking water, which most people pour down the drain.
If you prefer boiled sweet potatoes, cooking them whole with the skin on minimizes this loss. Keeping the skin intact acts as a barrier, slowing the rate at which potassium dissolves into the water. For the highest potassium content, baking or microwaving is your best bet.
How Sweet Potatoes Compare to Other Foods
Bananas are the food most people associate with potassium, but a medium banana contains about 451 mg, roughly 90 mg less than a baked sweet potato. A regular white potato actually leads the group: a medium baked potato with skin delivers over 900 mg of potassium, nearly double what a sweet potato provides.
Still, sweet potatoes hold their own among potassium-rich foods, and they bring additional nutrients (fiber, beta-carotene) that make them a strong choice beyond the potassium alone.
How Much Your Body Actually Absorbs
Not all the potassium listed on a nutrition label ends up in your bloodstream. Plant-based sources of potassium, including sweet potatoes, have a bioavailability of roughly 50 to 60%, compared to about 90% from animal products like meat and dairy. This means your body may absorb somewhere around 270 to 325 mg from a medium baked sweet potato rather than the full 542 mg.
The reason comes down to cell walls. Plant cells trap minerals inside structures that your digestive system has to break apart before the potassium becomes available. Potatoes have relatively porous cell walls compared to foods like legumes and peas, so they release their potassium more easily than many other plant foods. Cooking also helps by softening those cell walls, which is one more reason a baked sweet potato delivers more usable potassium than a raw one.
Why Potassium From Sweet Potatoes Matters
Potassium works as a counterbalance to sodium in the body. When sodium levels are high, blood vessels tend to constrict and blood pressure rises. Potassium stimulates a cellular pump in blood vessel walls that pushes sodium out and allows those vessels to relax, lowering pressure. This is why diets rich in potassium are consistently linked to healthier blood pressure levels, particularly for people who consume a lot of salt.
Most adults in the U.S. fall well short of the 4,700 mg daily target. A single sweet potato won’t close that gap on its own, but pairing it with other potassium-rich foods throughout the day, like beans, leafy greens, yogurt, and yes, bananas, adds up quickly. Two medium baked sweet potatoes alone would cover roughly a quarter of your daily needs before accounting for anything else on your plate.
Quick Reference by Serving Size
- 1 medium baked sweet potato (about 130g, skin on): ~542 mg potassium
- 1 cup cubed, baked: ~450 to 500 mg potassium
- 1 cup cubed, boiled: ~250 to 300 mg potassium (roughly half lost to water)
The USDA defines a standard medium sweet potato as about 5 inches long and roughly 130 grams. Larger sweet potatoes, which are common at grocery stores, can weigh 200 grams or more and will contain proportionally more potassium. If your sweet potato is noticeably bigger than your fist, you’re likely getting closer to 700 or 800 mg per potato when baked.