Spinach Calories & Nutrition Calculator

Raw and cooked spinach both have 23 kcal per 100g — one of the rare vegetables where cooking doesn't change the calorie density at all. But the practical difference is enormous: 1 cup of raw spinach weighs just 30g (7 kcal), while 1 cup of cooked spinach weighs 180g (41 kcal) because the leaves collapse during heating ^[1][2].

This means a 'cup of spinach' can vary by 6x in actual food weight depending on whether it's raw or cooked. For food journaling, always specify the form — raw or cooked — because selecting the wrong variant can cause a 6x error in nutrient tracking for the same measured volume.

Frozen spinach (29 kcal/100g) is slightly more calorie-dense per gram than fresh because it's blanched and partially dehydrated before freezing. A standard frozen spinach block (156g) has 45 kcal — roughly equivalent to 1 cup of cooked fresh spinach ^[3].

Raw spinach contains 2.71mg iron per 100g and cooked spinach has 3.57mg iron per 100g — numbers that look impressive compared to many vegetables. One cup of cooked spinach (180g) provides 6.4mg iron, which is 36% of the daily value on paper ^[2].

However, spinach iron is entirely non-heme (plant-based) iron, and spinach contains high levels of oxalic acid that bind to iron and reduce absorption. Studies suggest that only about 1.7–5% of spinach iron is actually bioavailable — compared to approximately 15–35% from animal sources like red meat.

For food journaling, log the full iron value (the USDA number). Your journal shows total dietary iron, and the body's absorption varies by meal composition — pairing spinach with vitamin C sources (lemon juice, tomatoes) can improve iron uptake, while calcium and tannins (tea, coffee) may reduce it further.

Raw spinach has 483mcg vitamin K per 100g — the third-highest vitamin K concentration among common vegetables after parsley (~1,640mcg) and kale (~817mcg). Cooked spinach retains nearly all of it at 494mcg per 100g because vitamin K is fat-soluble and heat-stable ^[1][2].

The practical impact: just 1 cup of raw spinach (30g) provides approximately 145mcg vitamin K — 121% of the daily value. One cup of cooked spinach (180g) provides 889mcg — 741% DV. Spinach is one of the most efficient vitamin K delivery vehicles available.

For food journaling, spinach contributes significant vitamin K at any serving size. Even a small handful in a smoothie or sandwich contributes well over 100% DV. This is useful tracking information for anyone monitoring their vitamin K intake patterns.

Raw spinach has 28.1mg vitamin C per 100g, which drops to 9.8mg per 100g after boiling and draining — a 65% reduction. Frozen spinach retains even less at 5.5mg per 100g because blanching before freezing destroys most of the heat-sensitive vitamin C ^[1][2][3].

For context, 1 cup of raw spinach (30g) provides about 8.4mg vitamin C (9% DV), while 1 cup of cooked spinach (180g) provides 17.6mg (20% DV). Despite the per-100g loss, the larger cooked serving still delivers more total vitamin C than a small raw serving.

For food journaling, if vitamin C tracking matters, prefer raw spinach in salads and smoothies. Steaming retains more vitamin C than boiling because less water contact reduces leaching. Adding lemon juice to cooked spinach adds vitamin C back (~5.8mg per tablespoon) while also improving iron absorption.

Raw spinach provides 194mcg folate per 100g — one of the richest food sources of this B-vitamin. One cup of cooked spinach (180g) provides 263mcg folate — 66% of the daily value from a single serving ^[1][2].

Frozen spinach unexpectedly contains 226mcg folate per 100g — 16% more than fresh raw spinach. This is because frozen spinach is typically harvested at peak maturity and flash-frozen, preserving folate levels that might degrade during the transport and shelf time of fresh spinach ^[3].

Boiling fresh spinach reduces folate to 146mcg per 100g — a 25% loss — because folate is water-soluble and leaches into the cooking liquid. For food journaling, frozen spinach used in cooking is actually the most folate-efficient form of spinach per gram, followed by raw, then boiled.