29.8g Protein and 164 kcal Boiled: Octopus Has
Boiled octopus delivers 29.8g protein per 100g at 164 kcal — a protein-to-calorie ratio of 18.2g per 100 kcal [1]. Only cuttlefish (32.5g/100g at 158 kcal) surpasses octopus for protein density among commonly eaten cephalopods. Among all seafood, octopus ranks in the top 5 for protein per serving.
A standard 3-oz portion (85g, approximately 2-3 tentacle pieces) provides 25.3g protein at just 139 kcal [1]. This is comparable to a 3-oz chicken breast (24.7g protein) but with nearly double the iron and 30x the vitamin B12.
Research on the nutritional composition of octopus species (Octopus hubbsorum) from the Pacific Ocean confirmed protein levels of 14-16g per 100g raw across multiple species, with essential amino acid profiles meeting or exceeding FAO/WHO reference standards [2].
One Tentacle Provides a Week's Worth of B12
Boiled octopus delivers 36.0mcg vitamin B12 per 100g — 1,500% of the daily value [1]. A single whole tentacle (approximately 60g cooked) provides 21.6mcg B12 — 900% DV. In practical terms, eating one octopus tentacle every 3-4 days would fully saturate the body's B12 stores.
The B12 concentration in octopus increases dramatically with cooking: from 20mcg raw to 36mcg per 100g boiled [1]. This is because B12 is heat-stable and concentrates as the tissue loses approximately 40% of its water during the typical 45-90 minute simmer that tenderizes octopus.
Dried octopus concentrates B12 even further to 72mcg per 100g — approaching beef liver territory (70.6mcg/100g) [1]. In Mediterranean and East Asian cuisines where dried octopus is common, even small amounts added to soups and stews contribute substantial B12.
Octopus Is the Richest Source of Heme Iron
Boiled octopus provides 9.48mg iron per 100g — 53% of the daily value [1]. This makes octopus the single richest source of heme iron among all commonly consumed seafood — surpassing mussels (6.7mg), oysters (7.8mg), and clams (2.9mg). Only dried octopus (19mg/100g) contains more.
A 3-oz serving (85g) delivers 8.1mg iron — 45% DV [1]. For comparison, 3 oz of beef sirloin provides 2.0mg, and 3 oz of chicken breast provides 0.4mg. Octopus delivers 20x the iron of chicken gram-for-gram.
The iron in octopus is predominantly in the heme form, bound to myoglobin in the muscle tissue. Octopus tentacles contain particularly high concentrations of myoglobin (the oxygen-binding protein in muscle), which accounts for the characteristically purple-red color of fresh octopus [2].
What 90 Minutes of Simmering Does to Octopus: Tough Collagen
Fresh octopus is notoriously tough — its muscle fibers contain dense cross-linked collagen that makes it chewy if undercooked. The traditional 45-90 minute simmer converts collagen to gelatin, transforming the texture from rubbery to tender [1].
During this long cooking process, octopus loses approximately 40% of its weight in water. This water loss concentrates every nutrient per gram: calories double (82 → 164), protein doubles (14.9 → 29.8g), and iron nearly doubles (5.3 → 9.5mg) per 100g [1]. The total nutrients in the same piece remain similar — only the per-gram density changes.
For tracking: if you weigh octopus raw before cooking, multiply by 0.60 to estimate the cooked weight, then use the boiled per-100g values. If you weigh after cooking, use the boiled values directly. The difference matters: 200g raw octopus ≈ 120g cooked, which is 164 kcal (raw math) or 197 kcal (if you incorrectly use raw per-100g on cooked weight) [1].
Double the Potassium of a Banana in Every 3-oz Serving of Pulpo
Boiled octopus delivers 630mg potassium per 100g — 13% DV [1]. A 3-oz serving provides 536mg potassium, while a medium banana provides approximately 422mg. Gram-for-gram, octopus has 1.7x the potassium density of the fruit most associated with this mineral.
Raw octopus starts at 350mg potassium per 100g [1]. Cooking concentrates this dramatically because potassium is water-soluble but is retained in the dense, collagen-rich tissue matrix rather than leaching into the cooking water — unlike many vegetables that lose potassium during boiling.
Combined with its high protein and low fat, octopus offers a unique potassium-to-calorie ratio: 3.84mg potassium per calorie — one of the highest ratios among any protein food. Compare to banana (3.8mg/kcal), spinach (11.5mg/kcal), or salmon (1.85mg/kcal) [1].
Octopus vs. Other Cephalopods & Seafood (per 100g Cooked)
| Nutrient | Octopus (boiled) | Cuttlefish | Squid | Mussels | Shrimp |
|---|---|---|---|---|---|
| Calories (kcal) | 164 | 158 | 175 | 172 | 99 |
| Protein (g) | 29.8 | 32.5 | 17.9 | 23.8 | 20.9 |
| Total Fat (g) | 2.1 | 1.4 | 7.5 | 4.5 | 1.3 |
| Iron (mg) | 9.5 | 10.8 | 1.2 | 6.7 | 0.3 |
| Vitamin B12 (mcg) | 36.0 | 5.4 | 1.3 | 24.0 | 1.7 |
| Potassium (mg) | 630 | 637 | 246 | 268 | 170 |
Practical Tips for Octopus
- 1
29.8g protein at 164 kcal per 100g boiled — octopus is the second-highest protein cephalopod, behind only cuttlefish (32.5g). More protein per gram than chicken breast [1].
- 2
One tentacle (60g cooked) delivers 900% of daily B12 (21.6mcg) — eating octopus once or twice a week fully covers B12 needs [1].
- 3
9.5mg iron per 100g (53% DV) — the highest heme iron in any common seafood. A 3-oz serving provides more iron than a 6-oz steak [1].
- 4
Octopus loses ~40% weight during cooking — 200g raw becomes ~120g cooked. Always clarify which state you're weighing for accurate logging [1].
- 5
630mg potassium per 100g boiled — double the potassium density of bananas. Octopus concentrates potassium during cooking instead of losing it [1].
Frequently Asked Questions — Octopus
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Important Notice
Nutritional values are based on USDA FoodData Central data for mollusks, octopus, common, raw (FDC 175103) and cooked, moist heat (FDC 175102). Grilled values are estimated from boiled data adjusted for additional moisture loss. Dried values are estimated from published analyses of dried octopus products. Actual values vary by species, origin, size, and cooking method. This tool is for informational and nutrition journaling purposes only — it is not a substitute for guidance from a qualified nutrition professional.
About the Author
Certified fitness professional and nutrition researcher with over 10 years of experience in the fitness and wellness industry. Founder of Food Nutrify, dedicated to making accurate, science-backed nutrition data accessible to everyone through free, easy-to-use calculators.
References & Sources
- [1] USDA FoodData Central (2024). Mollusks, octopus, common, raw (FDC 175103); cooked, moist heat (FDC 175102). U.S. Department of Agriculture, Agricultural Research Service.
- [2] Meza-Buendía AK, et al. (2019). Nutritional Analysis of Octopus hubbsorum B. (Cephalopoda: Octopodidae) from the Pacific Ocean. ResearchGate — Chapter 2.