Kale takes calcium and fiber; spinach answers with magnesium, folate and potassium
The two salad-aisle superstars are dead even on protein — about 2.9g per 100g raw each — and then split the board. Kale brings nearly four times the calcium (254mg vs 67mg), two and a half times the fiber (4.1g vs 1.6g) and more iron (1.6mg vs 1.1mg). Spinach counters with almost three times the magnesium (93mg vs 33mg), nearly double the folate (113µg vs 62µg), more potassium (460mg vs 348mg) and more vitamin A (306µg RAE vs 241µg RAE).
| Nutrient | Kale | Spinach |
|---|---|---|
| Energy (kcal) | 35 | — |
| Protein (g) | 2.92 | 2.91 |
| Total Fat (g) | 1.49 | 0.6 |
| Carbohydrate (g) | 4.42 | 2.64 |
| Fiber (g) | 4.1 | 1.59 |
| Sodium (mg) | 53 | 106.6 |
Source: Kale, raw (FDC ID 323505), Spinach, mature (FDC ID 1750353)
For calcium / bone support
Kale
254mg per 100g versus spinach's 67mg — and kale's low oxalate content means that calcium is also better absorbed.
For folate (pregnancy)
Spinach
113µg per 100g raw, nearly double kale's 62µg — folate is the nutrient spinach is quietly best at.
For magnesium and potassium
Spinach
Magnesium 93mg vs 33mg and potassium 460mg vs 348mg per 100g.
For fiber
Kale
4.1g vs 1.6g per 100g — kale's sturdier leaves carry roughly 2.5 times the fiber.
Kale and spinach barely overlap in their strengths: kale owns calcium, iron and fiber; spinach owns magnesium, folate and potassium. There's also an absorption wrinkle the raw numbers hide — spinach is high in oxalates, which bind much of its calcium and some of its iron, while kale is low-oxalate, so kale's mineral numbers translate to the body more faithfully. The practical answer for most people is rotation: both, alternating, covers the full spread.
At roughly 2.9g of protein per 100g each, neither green outmuscles the other — and kale is genuinely light at 35 kcal per 100g raw. The choice often comes down to how you eat them: kale's tough, fibrous leaves (4.1g fiber) hold up to massaging, roasting into chips and long braises, while tender spinach (1.6g fiber) wilts in seconds and disappears agreeably into smoothies, eggs and pastas — which makes it the easier green to eat in volume, where its folate and magnesium add up fast.
Energy
35
vs
—
kcal
Protein
2.92
vs
2.91
g
Total Fat
1.49
vs
0.60
g
Total Carbohydrate
4.42
vs
2.64
g
Dietary Fiber
4.10
vs
1.59
g
| A Kale, raw | Nutrient | Spinach, mature B |
|---|---|---|
| 35kcal | Energy | —kcal |
| 89.60g | Water | 92.43g+2.8 |
| 2.92g+0.0 | Protein | 2.91g |
| 1.49g | Total Fat | 0.60g |
| 4.42g | Total Carbohydrate | 2.64g |
| 4.10g+2.5 | Dietary Fiber | 1.59g |
| 53mg | Sodium | 106.60mg |
| 348mg | Potassium | 459.70mg+111.7 |
| 254mg+187.4 | Calcium | 66.64mg |
| 32.70mg | Magnesium | 92.96mg+60.3 |
| 55mg+14.4 | Phosphorus | 40.56mg |
| 1.60mg+0.5 | Iron | 1.05mg |
| 0.39mg | Zinc | 0.42mg+0.0 |
| 0.05mg | Copper | 0.08mg+0.0 |
| 0.92mg+0.5 | Manganese | 0.43mg |
| 241μgRAE | Vitamin A | 306μgRAE+65 |
| 0.66mg | Vitamin E | —mg |
| 0μg | Vitamin K | —μg |
| 0.11mg+0.0 | Thiamin | 0.08mg |
| 0.35mg+0.2 | Riboflavin | 0.19mg |
| 1.18mg+0.7 | Niacin | 0.51mg |
| 0.15mg | Vitamin B6 | 0.21mg+0.1 |
| 62μg | Folate | 113.40μg+51.4 |
| 390mg | Vitamin C | —mg |
Q. Which has more calcium, kale or spinach?
A. Kale, decisively: 254mg per 100g raw versus 67mg for spinach. Kale's calcium is also more bioavailable, because spinach's oxalates block much of its own calcium from being absorbed.
Q. Is spinach or kale better for iron?
A. By the numbers, kale: 1.6mg vs 1.1mg per 100g. Both contain non-heme iron that absorbs better alongside vitamin C, and spinach's oxalates further limit its iron uptake.
Q. Which is better for folate?
A. Spinach, with 113µg per 100g raw — nearly double kale's 62µg. That makes spinach the stronger pick during pregnancy or for anyone focused on folate.
Data source: USDA FoodData Central (Public Domain). All values per 100g, edible portion. Some USDA Foundation Foods records do not report an Energy (kcal) value.