How Many Calories Are in Spirulina? Nutrition Facts Explained
, by The ENERGYbits® Team, 8 min reading time
Dried spirulina runs about 290 to 300 calories per 100 grams, but a typical 3 gram serving is only around 9 calories. Here is the full macro breakdown, plus how to log it in a tracking app.
Nutrition Facts
How Many Calories Are in Spirulina? Nutrition Facts Explained
Nutrition data reports spirulina per 100 grams, which is roughly 33 times a normal daily serving.
Quick answerDried spirulina contains roughly 290 to 300 calories per 100 grams. Almost nobody eats 100 grams. A typical 3 gram daily serving is about 9 calories, and a single 250 mg tablet is 1 calorie. All figures are approximate and vary a little by batch and brand.
Calorie questions about spirulina usually start the same way. Someone looks up the nutrition data, sees a number near 290, and quietly panics. The number is real. It is also close to meaningless until you know what an actual serving looks like.
How many calories are in spirulina?
Nutrition databases list dried spirulina at roughly 290 to 300 calories per 100 grams. That is a reference amount used to compare foods on equal footing, not a suggested serving. One hundred grams of dried algae is a large quantity, closer to a third of a big bag than to a scoop.
Scale it to real life and the number becomes ordinary. A 3 gram serving works out to about 9 calories. A single 250 mg tablet is 1 calorie, less than a stick of gum. Even a generous 10 gram day lands near 30 calories.
What is in a 3 gram serving?
Protein does most of the work. Spirulina is roughly 60 to 70 percent protein by dry weight, so 3 grams delivers about 1.8 to 2 grams of protein. Carbohydrate sits well under 1 gram, fat is a fraction of a gram, and fiber and sugar are both negligible at this size.
Treat those numbers as approximate. Spirulina is grown, harvested and dried, and each of those steps shifts the final composition slightly, which is why two labels can differ by a few percent. If protein is your main interest, we break it down in our guide to how much protein is in spirulina.
Founder's note: "Algae is the most nutrient dense food on the planet, and that is exactly why the calorie count is so small," says Catharine Arnston, founder of ENERGYbits.
| Serving | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| 1 tablet (250 mg) | 1 | 0.1 to 0.2 g | about 0 g | about 0 g |
| 3 g serving | About 9 | 1.8 to 2 g | Under 1 g | About 0.2 g |
| 1 tablespoon (about 7 g) | About 20 | 4 to 4.9 g | About 1.7 g | About 0.5 g |
| 100 g | 290 to 300 | 60 to 70 g | About 24 g | About 8 g |
One ingredient, about 3 calories a tablet
ENERGYbits Spirulina is a single ingredient tablet with no fillers, no binders and no sugar. Just organically grown spirulina, so the serving math stays simple.
Shop ENERGYbits SpirulinaWhy is spirulina called nutrient dense instead of calorie dense?
Nutrient density describes how much nutrition a food delivers per calorie. Calorie density describes how much energy it packs per gram. Spirulina sits in an unusual corner of that map: very high nutrient density and, at real serving sizes, almost no calories.
For roughly 9 calories you get a couple of grams of complete protein along with iron, B vitamins, chlorophyll and phycocyanin, the blue pigment that gives spirulina its color. Few foods offer that ratio, which is why algae is treated as a nutrient source rather than an energy source.
Does spirulina fit keto and low calorie diets?
Yes to both, at normal servings. With well under 1 gram of carbohydrate in a 3 gram serving, spirulina will not move your daily carb total in any meaningful way, which is why it fits comfortably inside a ketogenic pattern. We work through the details in our article on whether spirulina is keto friendly.
Calorie deficit diets are an even easier fit. When you eat less, every calorie has to earn its place, and 9 calories carrying 2 grams of protein is about as efficient as food gets. We look at that trade in our piece on spirulina for weight loss.
How do you log spirulina in a calorie tracking app?
Log by weight, not by tablet count. Enter total grams, since brands press tablets at slightly different sizes and gram entries stay far more consistent across food databases. Twelve 1 gram tablets is simply 12 grams of spirulina.
Entries in these apps will disagree with each other by a few calories. Some pull generic reference data, some pull a specific brand label, and rounding rules vary. At this scale the difference is noise against your daily total, so pick a sensible entry and stay with it. Our daily dosage guide can help you settle on how many grams to log.
Will spirulina make you gain weight?
Not at the amounts people actually take. Adding 9 to 36 calories to your day is not enough to shift body weight in either direction. If the scale moves after you start algae, look at appetite, meal timing, sodium and water first. Those variables are much larger than a few calories of dried algae.
How does spirulina compare calorie for calorie?
Against other protein sources, spirulina looks high per 100 grams and tiny per serving. Whey protein powder is around 400 calories per 100 grams, chicken breast about 165, cooked lentils about 116. Spirulina lands near 290, but you eat 3 grams of it, not 100.
Against greens the picture reverses. Fresh spinach is about 23 calories per 100 grams, and roughly 91 percent of that weight is water. Remove the water and its calorie density per gram climbs into spirulina territory. Every dehydrated food looks calorie dense on paper.
Chlorella is nearly identical, generally landing in the same 290 to 300 calorie range per 100 grams with slightly less protein and a little more fiber.
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SubscribeFrequently asked questions
How many calories are in spirulina?
Dried spirulina contains roughly 290 to 300 calories per 100 grams, but that is a reference amount rather than a serving. A typical 3 gram daily serving works out to about 9 calories. Figures are approximate and vary slightly by batch and brand.
How many calories are in one spirulina tablet?
A 1 gram tablet is roughly 3 calories. Twelve tablets, a common daily amount, come to about 36 calories. Tablet weight differs between brands, so check your label if you want a precise number.
Will spirulina make me gain weight?
Not at normal servings. A few grams of spirulina adds somewhere between 9 and 36 calories to your day, which is far too small to change body weight on its own. Any movement on the scale is more likely to come from appetite, meal timing or water.
Does chlorella have the same calories as spirulina?
Very close. Chlorella generally falls in the same 290 to 300 calorie range per 100 grams, with slightly less protein and a little more fiber. At a 3 gram serving the difference is a calorie or two, so you can treat them the same way when tracking.
This article is for educational purposes and is not medical advice. If you are pregnant, nursing, taking medication, or managing a health condition, consult your healthcare provider before starting any supplement.
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