A one-cup serving of raw spinach contains about 7 calories. That makes it one of the lowest-calorie foods you can eat, even in generous portions. The number shifts depending on whether you’re eating it raw or cooked, though, because spinach shrinks dramatically with heat.
Raw vs. Cooked: Why the Numbers Look Different
The calorie gap between raw and cooked spinach comes down to volume. One cup of raw spinach weighs only about 30 grams, so it clocks in around 7 calories. But spinach loses so much water during cooking that one cup of raw leaves reduces to roughly a quarter cup once boiled or sautéed. A full cup of cooked spinach, then, represents about four cups of raw leaves packed down by heat.
That’s why the cooked number looks higher at first glance: one cup of boiled spinach contains about 41 calories, along with 5.4 grams of protein, 6.8 grams of carbohydrates, and 4.3 grams of fiber. You’re simply eating a lot more spinach by weight. Per 100 grams, raw spinach has 23 calories regardless of how you prepare it.
Full Nutrition Breakdown
Spinach is roughly 91% water, which explains its featherweight calorie count. Here’s what you get from each standard serving:
- 1 cup raw (about 30g): 7 calories, 0.9g protein, 1.1g carbs, 0.1g fat, roughly half a gram of fiber
- 1 cup cooked/boiled (about 180g): 41 calories, 5.4g protein, 6.8g carbs, 0.5g fat, 4.3g fiber
- 100 grams raw: 23 calories, 2.9g protein, 3.6g carbs, 0.4g fat, 2.2g fiber
Sugar content is minimal either way: 0.4 grams per 100 grams raw, under 1 gram per cup cooked. If you’re tracking carbohydrates, most of spinach’s carbs come from fiber rather than sugar.
Baby Spinach vs. Mature Spinach
If you’re wondering whether the tender baby spinach in salad bags differs from the larger, tougher mature leaves, the nutritional values are essentially the same. Baby spinach is simply harvested earlier, so the leaves are smaller and milder in flavor. Calorie and nutrient content per gram doesn’t meaningfully change.
Getting More From Your Spinach
Spinach is rich in iron, but your body absorbs only about 10% of the iron from plant foods like spinach. The reason is partly oxalates, naturally occurring compounds found at high concentrations in spinach (roughly 650 to 1,287 milligrams per 100 grams, depending on the variety). Oxalates bind to iron and calcium, reducing how much your body can actually use.
Pairing spinach with a source of vitamin C makes a real difference. Vitamin C converts plant-based iron into a form your gut absorbs more readily. Practical ways to do this: squeeze lemon juice over sautéed spinach, toss raw spinach in a salad with sliced bell peppers or tomatoes, or blend it into a smoothie with strawberries or orange juice. Cooking spinach also breaks down some of its oxalate content, which is one reason cooked spinach delivers more accessible nutrients per cup than raw.
How Spinach Compares to Other Greens
At 23 calories per 100 grams, spinach sits at the low end even among leafy greens. Kale comes in around 35 calories per 100 grams, romaine lettuce at about 17, and iceberg lettuce at roughly 14. The difference is that spinach packs considerably more protein, fiber, and micronutrients per calorie than most lettuces. A cup of cooked spinach delivers over 5 grams of protein, which is notable for a vegetable and useful if you’re building meals around plants.
For most people, the practical takeaway is simple: spinach adds almost no calories to a meal whether you toss a few handfuls into a salad, wilt it into a pasta sauce, or blend it into a smoothie. The main reason to pay attention to serving size isn’t calories but rather getting enough volume to benefit from its fiber and nutrients, which means cooked spinach tends to give you more per bowl than raw.