Spinach vs Kale: Nutrition, Calories & Best Choice
A side-by-side comparison of raw spinach and raw kale per 100 g and per cup — calories, protein, fiber, iron, calcium, vitamin K, oxalates, glycemic index, and which green fits your goals.
Written by Victura Nutrition TeamReviewed by Victura Editorial ReviewLast updated Oct 13, 2026
Quick answer
Both are nutrient-dense, and the honest answer is whichever one you eat regularly. Kale has more vitamin C (120 mg vs 28 mg per 100 g), more vitamin K, more fiber, and calcium your body absorbs far better. Spinach has more folate, iron, magnesium, and potassium, and it is milder in taste.
A side-by-side comparison of raw spinach and raw kale per 100 g and per cup — calories, protein, fiber, iron, calcium, vitamin K, oxalates, glycemic index, and which green fits your goals.
Key takeaways
- Kale has 49 calories per 100 g raw and spinach 23; a cup of either stays under 35.
- Kale leads on vitamin C, vitamin K, fiber, and usable calcium; spinach leads on folate, iron, and magnesium.
- Spinach is high in oxalate (about 600-750 mg per 100 g); kale is low, which matters for kidney stone history.
- Both are very low glycemic, keto friendly, and useful for weight loss at realistic portions.
- Spinach blends mild in smoothies; choose baby or lacinato kale for salads and soups.
Spinach vs Kale: The Evidence-Based Comparison
Research-backedSpinach and kale are the two dark leafy greens most households in the US and Canada actually keep on hand. They look interchangeable in a salad bowl, but they differ in fiber, vitamin C, calcium availability, and oxalates. This comparison uses raw, mature leaves and standard USDA reference values per 100 g, with US household portions beside every number.
Calories and macros: close, but not identical
Per 100 g, raw kale provides 49 calories and raw spinach 23. The gap looks large until you convert to real portions: one cup of raw spinach is 30 g (about 1.1 oz) at roughly 7 calories, while one cup of chopped raw kale is 67 g (about 2.4 oz) at roughly 33 calories. Both are among the lowest energy-density foods in the produce aisle, and both fill a plate for very few calories.
Kale carries more fiber (3.6 g vs 2.2 g per 100 g) and more total carbohydrate, which is why it also has more net carbs per cup. Protein depends on which USDA release you read: SR Legacy lists 4.3 g per 100 g for raw kale against 2.9 g for raw spinach, while the newer Foundation Foods entry for kale is closer to 2.9 g. Either way, a cup of either green is a volume food, not a protein source.
Bottom line: Raw spinach is lighter per cup and milder in flavor; raw kale is denser, higher in fiber and vitamin C, and still low enough in carbs to fit keto and diabetes-friendly patterns.
Side-by-side nutrition: spinach vs kale (raw, per 100 g)
All values are per 100 g raw unless the row states otherwise. Cup equivalents use 30 g for 1 cup raw spinach and 67 g for 1 cup chopped raw kale.
| Nutrient (raw) | Spinach | Kale |
|---|---|---|
| Calories | 23 kcal | 49 kcal |
| Protein | 2.9 g | 4.3 g |
| Total fat | 0.4 g | 0.9 g |
| Carbohydrates | 3.6 g | 8.8 g |
| Fiber | 2.2 g | 3.6 g |
| Net carbs (approx.) | 1.4 g | 5.2 g |
| Vitamin A (RAE) | 469 mcg (52% DV) | 500 mcg (56% DV) |
| Vitamin C | 28 mg (31% DV) | 120 mg (133% DV) |
| Vitamin K | 483 mcg (402% DV) | 705 mcg (588% DV) |
| Folate | 194 mcg DFE (49% DV) | 141 mcg DFE (35% DV) |
| Calcium | 99 mg (8% DV) | 150 mg (12% DV) |
| Iron | 2.7 mg (15% DV) | 1.5 mg (8% DV) |
| Magnesium | 79 mg (19% DV) | 47 mg (11% DV) |
| Potassium | 558 mg (12% DV) | 491 mg (10% DV) |
| Oxalates | High (about 600-750 mg) | Low |
| Glycemic index | Not established; estimated very low | Not established; estimated very low |
| Calories per 1 cup raw | 7 kcal (30 g / 1.1 oz) | 33 kcal (67 g / 2.4 oz) |
| Protein per 1 cup raw | 0.9 g | 2.9 g |
| Fiber per 1 cup raw | 0.7 g | 2.4 g |
| Pros | Highest folate and magnesium of the two; mild taste; cheap frozen options | Highest vitamin C and vitamin K; more fiber; low oxalate; sturdy texture |
| Cons | High oxalate; calcium poorly absorbed; wilts fast | Bitter raw; tougher stems; more carbs per cup |
| Best for | Smoothies, eggs, pasta, folate needs, low-calorie volume | Salads, soups, chips, low-oxalate diets, vitamin C and K needs |
Vitamins: kale wins on C and K, spinach on folate
Vitamin K is the headline number on both sides. Kale supplies about 705 mcg per 100 g, roughly 588% of the daily value, and spinach about 483 mcg, or about 402%. Both are far above what most adults need in a day, and both are safe everyday foods for most people.
- Vitamin C: kale 120 mg vs spinach 28 mg per 100 g, making kale the stronger raw source.
- Folate: spinach 194 mcg DFE vs kale 141 mcg DFE per 100 g, so spinach leads on a nutrient that matters before and during pregnancy.
- Vitamin A: essentially tied at 469 mcg RAE for spinach and 500 mcg RAE for kale, delivered mostly as beta-carotene.
- Heat caveat: vitamin C and folate are water-soluble and heat-sensitive, so boiling either green and pouring off the water lowers both.
Minerals: spinach leads on iron and magnesium, kale on usable calcium
The label numbers favor spinach for iron (2.7 mg vs 1.5 mg per 100 g), magnesium (79 mg vs 47 mg), and potassium (558 mg vs 491 mg). Kale shows more calcium (150 mg vs 99 mg), but the more useful fact is how much of that calcium your body can absorb.
Spinach is high in oxalic acid, which binds calcium and drops absorption to roughly 5%. Kale is low in oxalate and its calcium is absorbed at roughly 40-60%, several times better. If calcium is your reason for choosing a green, kale is the practical winner even though the label gap looks modest. The same oxalate effect reduces iron absorption from spinach, which is why food pairings matter.
Oxalates: the difference that changes recommendations
Spinach is one of the higher-oxalate vegetables at roughly 600-750 mg per 100 g raw. Kale sits firmly in the low-oxalate group. For most people this is irrelevant, but for anyone with a history of calcium oxalate kidney stones it usually decides the choice.
Boiling spinach for a few minutes and discarding the cooking water removes a meaningful share of oxalate, and it works better than steaming or sautéing. It does not turn spinach into a low-oxalate food, though, so kale remains the lower-risk option. If you have kidney stone history or take blood-thinning medication such as warfarin, talk with your clinician about how much vitamin K-rich greens to include.
Blood sugar, glycemic index, and keto
Neither spinach nor kale has an assigned glycemic index in the major international GI tables, because the carbohydrate per realistic portion is too small to test meaningfully. Estimates place leafy greens at a very low GI, and a cup of either contributes well under 5 g net carbs. For practical purposes, both are blood-sugar friendly, keto compatible, and useful in weight-loss plans.
Cooking, portions, and smoothies
How you prepare each green changes the comparison more than the raw numbers do.
- Steaming or a quick sauté for 2-3 minutes keeps more vitamin C and folate than boiling, which leaches them into the water.
- Cooked volumes shrink sharply: 1 cup of cooked spinach is about 180 g and 1 cup of cooked kale about 130 g. Watch added butter or oil, which multiplies calories quickly.
- Frozen spinach and frozen kale are frozen soon after harvest, so they retain most nutrients and often cost less. Check for added salt or sauces.
- For smoothies, spinach blends smooth and tastes mild, while kale, especially curly kale, is bitter and fibrous. Use baby kale or lacinato (Dino) kale and blend longer if you prefer kale.
How People Actually Use Spinach and Kale
Community insightWhat Victura users do with each green
Anonymized meal logs show two clear patterns. Spinach is the blending green: it turns up in smoothies, scrambled eggs, pasta sauces, and soups, often straight from the freezer. Kale is the texture green: massaged salads, bean soups, grain bowls, and oven-baked chips.
Logged portions for both are smaller than people expect. A typical raw spinach serving is about 1 cup (30 g / 1.1 oz), and a typical cooked kale side is about 1/2 cup (roughly 65 g / 2.3 oz). Both land under 40 calories before anything is added to the pan or blender.
Taste and texture decide more than the numbers
The nutrient gaps between these two greens are real but modest. What usually determines which one stays in your diet is bitterness and chew.
- Raw spinach is mild, soft, and almost sweet when young, and it wilts into nearly nothing.
- Raw curly kale is peppery and tough; it needs dressing, massage, or heat to soften.
- Lacinato (Dino) kale and baby kale sit in the middle: sturdier than spinach, far less bitter than mature curly kale.
- Cooked, the gap narrows. Both turn soft, and kale's bitterness mellows after 5-8 minutes in a pan or pot.
Swaps that work, and one that does not
- In soups, stews, curries, and stir-fries, swap freely, but add kale 3-4 minutes earlier than you would spinach.
- In smoothies, use spinach if you want the greens to disappear; choose baby kale only if you enjoy a greener, slightly bitter flavor.
- In eggs, quiches, and pasta, spinach is the safer substitute because it wilts fast and releases less water.
- In salads, kale is the sturdier base and holds dressing for a day without collapsing, while spinach needs dressing right before serving.
- In baked kale chips, do not substitute spinach. It burns before it crisps.
A simple way to use both
Keep a bag of frozen spinach for cooking and a bunch of kale for salads and soups. Rotating them gives you kale's vitamin C, vitamin K, and low oxalate load alongside spinach's folate, magnesium, and iron without leaning on either one. If you track intake in the Victura app, log the raw weight when you can, because cooked cup measurements vary widely depending on how long the greens were cooked.
References
- Spinach, raw — FoodData Central(usda)
- Kale, raw — FoodData Central(usda)
- Vitamin K — Fact Sheet for Consumers (NIH Office of Dietary Supplements)(nih_ods)
- Iron — Fact Sheet for Consumers (NIH Office of Dietary Supplements)(nih_ods)
- Heaney RP, Weaver CM, Recker RR. Calcium absorbability from spinach. Am J Clin Nutr.(pubmed)
- Mitchell T, et al. Dietary oxalate and kidney stone formation. Am J Physiol Renal Physiol.(pubmed)
- Vegetables and Fruits — Harvard T.H. Chan School of Public Health(harvard)
- Kidney stones — Symptoms and causes (Mayo Clinic)(mayo_clinic)
Frequently asked questions
People also ask
Which is healthier, spinach or kale?
Both are nutrient-dense, and the honest answer is whichever one you eat regularly. Kale has more vitamin C (120 mg vs 28 mg per 100 g), more vitamin K, more fiber, and calcium your body absorbs far better. Spinach has more folate, iron, magnesium, and potassium, and it is milder in taste. If you have a history of calcium oxalate kidney stones, talk with your clinician or a registered dietitian before making either green a daily habit, because spinach is a high-oxalate food.
Is kale better than spinach?
Not across the board. Kale wins on vitamin C, vitamin K, fiber, and bioavailable calcium. Spinach wins on folate, iron, magnesium, and potassium, and it has fewer calories per cup. Kale is also bitter when raw, which makes it harder for some people to eat often. Consistency matters more than the small gaps between them.
Can I substitute kale for spinach?
Yes in soups, stews, curries, and stir-fries, though kale needs 3-4 extra minutes of cooking. In salads, kale holds up better while spinach wilts faster. In smoothies, spinach disappears while kale stays green and slightly bitter, so use baby or lacinato kale for that swap. Do not swap kale into baked chips in place of spinach.
Is spinach or kale better for iron?
Spinach shows more iron per 100 g (2.7 mg vs 1.5 mg), but its oxalates bind iron and reduce how much you absorb. Kale's lower oxalate content means more of its iron is available. Pair either green with vitamin C sources such as citrus, tomatoes, or bell peppers, and keep tea and coffee away from the meal. Ask your clinician if you have iron deficiency.
Which has more protein, spinach or kale?
On USDA SR Legacy values, raw kale has 4.3 g protein per 100 g and raw spinach 2.9 g. Per typical cup, that is about 2.9 g for kale and 0.9 g for spinach. Neither green should be counted as a main protein source; treat both as low-calorie volume foods that support a meal.
Which is better for weight loss, spinach or kale?
Both work well because both are extremely low in calories by volume. Spinach is lighter per cup at roughly 7 calories versus 33 for kale, so it adds more bulk for less energy. Kale brings more fiber (3.6 g vs 2.2 g per 100 g), which can support fullness. Choose the one you will actually eat several times a week.
Is kale or spinach better for smoothies?
Spinach, for most people. It tastes mild, blends smooth in a standard blender, and does not darken a fruit smoothie much. Kale works but stays greener and more bitter, especially curly kale. If you prefer kale, use baby or lacinato kale and blend for at least 60 seconds so the fibers break down.
Are spinach and kale keto friendly?
Yes. A cup of raw spinach has roughly 1.4 g net carbs and a cup of raw kale about 5 g, so both fit strict keto targets. Cooked portions weigh more because the leaves shrink, but the carbohydrate per cup stays low. Watch what you cook them in, since butter and oil add calories rather than carbs.
Do you lose nutrients when you cook spinach or kale?
Some, mainly vitamin C and folate, which are heat-sensitive and water-soluble. Steaming or a quick sauté for 2-3 minutes preserves more than boiling, because boiling leaches nutrients into water you pour away. Vitamin K, minerals, and fiber hold up well to cooking, and cooked greens are easier to eat in larger amounts.
Is spinach or kale higher in oxalates?
Spinach, by a wide margin: roughly 600-750 mg per 100 g raw compared with low levels in kale. Oxalate binds calcium and can raise the risk of calcium oxalate kidney stones in susceptible people. Boiling spinach and discarding the water lowers oxalate without eliminating it, so kale remains the lower-oxalate choice. If you have a history of kidney stones, confirm your individual intake target with your clinician.
How many calories are in a spinach vs kale?
Per 100 g raw, spinach has 23 calories and kale has 49. Per typical cup, raw spinach is about 7 calories (30 g) and chopped raw kale about 33 calories (67 g), so both are very low-calorie greens.
Which has more calcium, spinach or kale?
Kale lists more calcium (150 mg vs 99 mg per 100 g), but spinach is high in oxalate, which binds calcium and drops absorption to roughly 5%. Kale's calcium is absorbed at roughly 40-60%, so kale delivers more usable calcium overall.
How we review this guide
- Written by
- Victura Nutrition Team
- Reviewed by
- Victura Editorial Review
- Reference sources
- 10
- Last updated
- Oct 13, 2026
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