Tool
Iron contribution estimator.
Spirulina is iron-rich for a food, but you eat it by the gram. Here's a calmer view of what your dose actually contributes.
Estimated iron contribution
95.2% of daily RDA
A substantial contribution — be mindful of total intake from all sources.
- Total iron in dose
- 84 mg
- Estimated absorption
- 17.14 mg (20%)
- Your daily RDA
- 18 mg
- Iron in 100 g spirulina
- ~28 mg
What this calculator does
It compares your daily spirulina dose against your recommended daily allowance for iron (RDA) based on age, sex, and life stage. It uses a published value of approximately 28 mg of iron per 100 g of dried spirulina, which is the typical figure for well-grown Arthrospira platensis.
It also adjusts for absorption: spirulina’s iron is non-haem, so absorption is modest (~10–15%) but improves with vitamin C and worsens with coffee, tea, and dairy.
How to read the result
- Under 10% — spirulina is a contributor, not a primary source. Useful as one ingredient among many.
- 10–25% — meaningful daily contribution. Pair with vitamin C foods to get the upper end.
- Above 25% — substantial contribution; pay attention to other sources to avoid over-supplementing.
Honest caveats
Iron content varies meaningfully between brands (we’ve seen reported values from 18 mg to 35 mg per 100 g). Bioavailability also depends on what else you eat in the same meal. This calculator gives you a rough order of magnitude, not a precise prescription.
If you’ve been diagnosed with iron-deficiency anaemia, this tool is not a replacement for clinical management. See your doctor.