Spinach is one of the richest sources of potassium you can eat. A single cup of cooked spinach delivers about 839 milligrams of potassium, which is nearly twice the amount in a medium banana. Whether raw or cooked, spinach packs a significant potassium punch, though the form you eat it in affects how much you actually absorb.
How Much Potassium Is in Spinach
One cup of boiled spinach (drained, without salt) contains roughly 839 mg of potassium. To put that in perspective, a medium banana, the food most people associate with potassium, has about 451 mg. So a serving of cooked spinach gives you nearly double.
Raw spinach has potassium too, but you’d need to eat a lot more volume to match the cooked version. Cooking wilts spinach dramatically. What fills an entire salad bowl raw shrinks to a single cup when boiled. That concentration is why cooked spinach appears to have so much more potassium per serving.
How Well Your Body Absorbs It
Having potassium in a food doesn’t guarantee your body uses all of it. Researchers measure something called bioaccessibility, which is how much of a nutrient actually becomes available during digestion. Spinach scores well here. Among common fruits and vegetables tested, spinach had one of the highest potassium bioaccessibility rates, alongside tomatoes and zucchini. The average across fruits and vegetables studied was about 67%, and leafy greens like spinach ranked at the top.
One important wrinkle: cooking method matters more than you might expect. In lab digestion tests, 100 grams of raw spinach yielded about 117 mg of bioaccessible potassium. That same amount of spinach, when boiled, dropped to roughly 39 to 49 mg of bioaccessible potassium per 100 grams. Boiling leaches potassium into the cooking water. If you want to retain more potassium, steaming or sautéing are better options than boiling, or you can use the cooking liquid in soups or sauces.
Do Oxalates Block Potassium Absorption?
Spinach is famously high in oxalates, compounds that bind to certain minerals and reduce how well your body absorbs them. This is a well-known issue for calcium and iron in spinach, where insoluble oxalate crystals form in the gut and pass through unabsorbed. But potassium behaves differently. Oxalates form soluble salts with potassium, not insoluble ones. This means oxalates don’t trap potassium and carry it out of your body the way they do with calcium. So while spinach isn’t a great source of calcium because of its oxalate content, its potassium remains largely available for absorption.
How Spinach Compares to Other High-Potassium Foods
Spinach stands out even among potassium-rich foods. Here’s how one cup of cooked spinach stacks up:
- Cooked spinach: 839 mg per cup
- Medium banana: 451 mg
Other strong sources include sweet potatoes, white beans, and avocados, but spinach is among the most potassium-dense vegetables available. It’s also low in calories, which makes it an efficient way to boost your intake without adding much to your daily energy total.
Potassium, Spinach, and Kidney Health
Because spinach is so rich in potassium, people with kidney disease sometimes wonder whether they need to avoid it. The National Kidney Foundation notes that leafy greens like spinach are indeed high in potassium, but most people with chronic kidney disease do not need to limit them. The amount of potassium you can safely eat depends on your stage of kidney disease and, if applicable, the type of dialysis you receive. If your blood potassium levels are running high, your care team will let you know how much to cut back. For everyone else, spinach’s potassium content is a benefit, not a concern.
Getting the Most Potassium From Spinach
If potassium intake is your goal, a few practical choices make a difference. Eating cooked spinach gives you far more potassium per serving than raw, simply because you consume more leaves in a sitting. Steaming or sautéing retains more potassium than boiling, since less leaches into water. And if you do boil spinach, saving the cooking liquid for a broth or sauce captures much of the potassium that would otherwise go down the drain.
Adding spinach to smoothies, omelets, or grain bowls are all easy ways to work it in regularly. Because your body absorbs spinach’s potassium efficiently compared to many other plant foods, even modest servings contribute meaningfully to your daily intake. Most adults need around 2,600 to 3,400 mg of potassium per day, so a single cup of cooked spinach covers roughly a quarter to a third of that target.