Blueberries are a low-calorie fruit with a modest iron content that many people overestimate because of their dark color. In reality, 100 g of raw blueberries contains only about 0.28 mg of iron — roughly 1.5% of the adult Daily Value. This Blueberry Iron Calculator helps you turn any serving size you actually eat (grams, ounces, cups, or handfuls) into a precise milligram figure.
Simply enter your portion, choose fresh or frozen berries, and optionally check your absorption context to see an estimated amount your body may use. The tool instantly reports total iron, percent Daily Value, and how many blueberry servings it would take to reach the 18 mg daily target.
This is a handy companion for meal planning, pregnancy nutrition check-ins, plant-based diet reviews, or anyone tracking micronutrients alongside their calorie budget.
Blueberry Iron Calculator
Estimate the iron content of fresh or frozen blueberries by serving size.
How the Calculation Works
This calculator converts your serving size to grams using standard weight equivalents: 1 ounce = 28.35 g, 1 cup of fresh blueberries ≈ 148 g, and 1 average handful ≈ 60 g. It then multiplies the gram weight by the iron density of the berry type you selected.
For raw blueberries, USDA FoodData Central lists about 0.28 mg of iron per 100 g. Frozen unsweetened blueberries contain slightly more — around 0.32 mg per 100 g — because freezing removes some water, concentrating minerals.
The core formula is simple:
Iron (mg) = serving weight (g) × iron per 100 g (mg) ÷ 100
After computing iron, the tool divides the result by 18 mg — the FDA Daily Value for iron — to show the percentage one serving contributes to an adult’s daily need.
How to Read Your Results
The main result line gives you the total milligrams of iron in your portion. Four quick-reference stats follow it:
- Iron — milligrams in the serving you entered.
- Daily Value — percent of the 18 mg reference this supplies.
- Est. absorbed — an illustrative estimate using a 15% baseline absorption for non-heme iron, adjusted for vitamin C and tea/coffee if checked.
- To reach 18 mg — the number of identical servings you would need to hit the full daily target.
The step-by-step breakdown below the stats shows the multiplication and division used so you can verify or adapt it.
| Serving | Approx weight | Iron (raw) | Iron (frozen) |
|---|---|---|---|
| 1 handful | 60 g | 0.17 mg | 0.19 mg |
| 1 oz | 28.35 g | 0.08 mg | 0.09 mg |
| 100 g | 100 g | 0.28 mg | 0.32 mg |
| 1 cup | 148 g | 0.41 mg | 0.47 mg |
| 1 pint (2 cups) | 296 g | 0.83 mg | 0.95 mg |
Worked Examples
Example 1: Breakfast bowl with 1½ cups of raw blueberries. Weight = 1.5 × 148 g = 222 g. Iron = 222 × 0.28 ÷ 100 = 0.62 mg. That's just 3.4% of the Daily Value. If you add sliced kiwi or a glass of orange juice, the estimated absorbed iron rises from roughly 0.09 mg to 0.15 mg.
Example 2: 3 oz of frozen blueberries in a smoothie. Weight = 3 × 28.35 g = 85.05 g. Iron = 85.05 × 0.32 ÷ 100 = 0.27 mg — about 1.5% of the 18 mg DV. You'd need roughly 67 smoothies of the same size to meet your daily iron target, which shows why blueberries alone can't carry your iron intake.
Factors That Affect Iron Absorption
Blueberries contain non-heme iron, the form found in plant foods. Non-heme iron is absorbed less efficiently than heme iron from meat, typically 10–20% depending on meal composition and your iron stores. The calculator's "Est. absorbed" stat starts from a 15% baseline. If you check the vitamin C option, it multiplies absorption by 1.6; if you check the tea/coffee option, it cuts it to 40% of baseline.
Keep in mind this is a learning tool, not a lab measurement. Actual absorption depends on many variables, including your current ferritin levels, stomach acid, polyphenols, calcium, and the overall mix of foods in the meal.
Practical tip: Blueberries contain polyphenols (anthocyanins) that may mildly reduce iron absorption when eaten in large amounts. Pairing them with a vitamin C source such as citrus, kiwi, or strawberries can offset this effect.
Frequently Asked Questions
Are blueberries a good source of iron? No, blueberries are low in iron. One cup supplies only about 0.41 mg, which is a little over 2% of the adult Daily Value. They are better known for fiber, vitamin C, and antioxidants.
Does frozen fruit have more iron than fresh? Slightly, because freezing removes water and concentrates solids. The difference is small — about 0.04 mg per 100 g — so it rarely changes dietary planning in a meaningful way.
Can blueberries help with iron deficiency? They contribute a little iron and vitamin C, but the amount is too small to correct anemia. Focus on iron-fortified cereals, legumes, pumpkin seeds, and — if appropriate — lean meat or fish. Compare with tools like mango iron, walnut iron, or pasta iron to see how other plant foods stack up.
Why does the calculator show an "absorption" estimate? Iron from plants isn't fully absorbed. The estimate helps you understand that 0.41 mg of iron does not equal 0.41 mg absorbed. Use it as an educational approximation, not a medical figure.
Additional Resources
For authoritative nutrient values, search "blueberries, raw" or "blueberries, frozen" in USDA FoodData Central. The NIH Office of Dietary Supplements iron fact sheet explains absorption, deficiency, and recommended intakes. For a general overview of the fruit, see the Wikipedia article on blueberries.