Spinach vs kale: which green wins the index?

Spinach and kale are the two greens people argue about most, and on our index the argument is close to a photo finish. Spinach, raw scores a perfect 100 on the NutriVerdict Nutrient Density Score. Kale, raw sits one point behind at 99. Both earn a five star rating, both are extremely low in calories, and both deliver more nutrition per calorie than almost anything else in our database. But a one point gap on a summary score hides some real differences underneath. Depending on which nutrient you care about, the winner flips.

The headline numbers

Per 100 grams, spinach carries 23 calories and kale carries 35. That 12 calorie difference sounds trivial, and at the plate it is, but it matters for a per-calorie score. Spinach packs its nutrients into fewer calories, which is a big part of why it edges kale on the index. Kale answers with more fiber, 4.1 grams per 100 grams against spinach's 2.2, and noticeably less sodium, 53 milligrams versus 79.

Here is the side by side from the USDA FoodData Central values behind our scores, all per 100 grams raw:

• Density score: spinach 100, kale 99
• Calories: spinach 23, kale 35
• Vitamin A: spinach 469 micrograms, kale 241 micrograms
• Vitamin C: spinach 28.1 milligrams, kale 93.4 milligrams
• Calcium: spinach 99 milligrams, kale 254 milligrams
• Iron: spinach 2.71 milligrams, kale 1.6 milligrams
• Potassium: spinach 558 milligrams, kale 348 milligrams
• Magnesium: spinach 79 milligrams, kale 33 milligrams

Vitamin A: spinach takes it

Spinach delivers 469 micrograms of vitamin A per 100 grams, nearly double kale's 241 micrograms. Against a daily value of 900 micrograms, a 100 gram portion of raw spinach covers roughly half of a day's vitamin A for about the calories in a stick of gum. Both greens carry the vitamin-a-rich tag in our database, so this is a win by margin, not a knockout. If vitamin A is your priority, spinach is the stronger pick per gram and per calorie.

Vitamin C: kale runs away with it

This is kale's signature stat. At 93.4 milligrams per 100 grams, raw kale clears the entire 90 milligram daily value for vitamin C in a single 100 gram portion. Spinach offers a respectable 28.1 milligrams, but kale delivers more than three times as much. Vitamin C is also sensitive to heat and cooking water, which is one more argument for eating kale raw in salads or barely wilted rather than boiled.

Calcium: kale again, by a wide margin

Kale carries 254 milligrams of calcium per 100 grams to spinach's 99. That alone would make kale the better calcium source, but the gap is even larger in practice because of oxalate, which we cover below. If you eat little or no dairy and are shopping the produce aisle for calcium, kale belongs on your list. Our guide to calcium beyond dairy goes deeper on which plant foods actually move the needle.

Iron: spinach on paper, with a caveat

Spinach lists 2.71 milligrams of iron per 100 grams against kale's 1.6, which is 15 percent of the 18 milligram daily value versus about 9 percent. On the label, spinach wins. The caveat is the same one that complicates its calcium story: oxalate.

The oxalate context

Spinach is well known as one of the highest oxalate vegetables, while kale is a low oxalate green. Oxalate is a naturally occurring plant compound that binds minerals like calcium and iron in the gut, which reduces how much of them your body can actually absorb from that food. Our density scores are built from measured nutrient content, so they reflect what is in the leaf, not what survives absorption. That means spinach's calcium and iron numbers are best read as ceilings, while kale's calcium is both higher on paper and more available in practice. None of this makes spinach a bad food. It simply means that if calcium or iron absorption is the specific reason you are eating a green, kale is the more reliable vehicle, and spinach earns its keep through vitamin A, folate, potassium, and magnesium instead.

So which green wins?

On the index, spinach wins by a single point, 100 to 99, because it squeezes slightly more total nutrition into fewer calories. Nutrient by nutrient, it is a split decision. Spinach takes vitamin A, potassium, magnesium, and label iron. Kale takes vitamin C, calcium, fiber, and the absorption argument. The honest answer is that this is a rivalry where both sides win, and the smartest move is rotation: spinach into eggs, soups, and smoothies where its soft leaves disappear, kale into salads and sautes where its sturdier structure holds up.

If you want to run this matchup yourself, or pit either green against arugula, collards, or Swiss chard, load them into our compare tool and see the full nutrient panels side by side. And to see where both greens land against the rest of the field, our leafy greens ranking scores every green in the database from top to bottom.