Blackberries are a tasty low-calorie fruit, but people tracking micronutrients often wonder whether they contribute meaningful iron. This calculator converts any serving size — grams, ounces, or cups — into an estimated iron value using the USDA nutrient database figure of 0.62 mg of iron per 100 g of raw blackberries. It also shows what percentage of your daily iron target that serving covers, so you can plan meals and snacks with a clearer picture of your micronutrient intake.
Whether you are following a plant-based diet, monitoring iron for anemia risk, or simply logging foods in a nutrition app, this tool gives you a fast, reliable estimate. Choose your serving size, pick the iron target that matches your needs (FDA Daily Value, adult male, pregnancy, or other categories), and press Calculate. The result includes a breakdown of the math so you can see exactly how the estimate was derived and compare different portion sizes.
🫐 Blackberry Iron Calculator
Estimate the iron in any serving of raw blackberries and see how it fits your daily target.
Step-by-Step Guide
Start by choosing your serving size:
- Use the quick-fill buttons for 1 cup (144 g), ½ cup (72 g), 100 g, or 1 oz (28 g) if one of those fits your meal.
- Alternatively, type any amount into the number field and choose the matching unit from the dropdown — grams, ounces, or cups.
- Select the daily iron target that applies to you: the FDA Daily Value (18 mg), the adult male RDA (8 mg), the adult female RDA (18 mg), pregnancy (27 mg), childhood (10 mg), or teen female needs (15 mg).
- Press Calculate iron. The result shows the total iron in milligrams, the percentage of your chosen target, and a breakdown of the conversion and math.
- Use Copy result to save the answer for a food log or note.
The calculator assumes raw, whole blackberries with the USDA nutrient profile. If your blackberries are frozen without added sugar, the iron value is very similar; if they are cooked and drained, the concentration can shift slightly because water is lost.
How the Estimate Works
The calculation is based on the United States Department of Agriculture (USDA) FoodData Central entry for raw blackberries, which lists 0.62 mg of iron per 100 g of fruit. To estimate the iron in your serving, the calculator first converts your chosen unit into grams:
- 1 ounce = 28.3495 grams
- 1 cup of raw blackberries ≈ 144 grams
Then it applies the simple proportion:
Percent of target = (Iron mg ÷ daily target mg) × 100
For example, a 100-gram serving is exactly 0.62 mg, while a 72-gram half-cup is 0.72 × 0.62 = 0.45 mg. This gives you a transparent, reproducible estimate that you can verify with any nutrition database. For more detail on the nutrient values, see the USDA FoodData Central entry for raw blackberries.
Reference Table: Iron in Common Blackberry Servings
| Serving | Weight | Iron (mg) | % of FDA DV (18 mg) |
|---|---|---|---|
| 1 oz | 28 g | 0.17 mg | 1.0% |
| ½ cup | 72 g | 0.45 mg | 2.5% |
| 100 g | 100 g | 0.62 mg | 3.4% |
| 1 cup | 144 g | 0.89 mg | 5.0% |
| 1 pint | 288 g | 1.79 mg | 9.9% |
As the table shows, blackberries are not an iron-dense food, but they can still contribute a few percent of your daily need, especially in larger servings or when combined with other iron sources.
Iron Absorption & Practical Tips
Blackberries contain non-heme iron, the form found in plants. Non-heme iron is absorbed less efficiently than the heme iron in meat, fish, and poultry — estimates typically range from about 2% to 20% depending on your iron status and the rest of the meal. That does not make plant sources unimportant; it just means the context matters.
Other practical points: cooking blackberries in a cast-iron skillet can slightly raise their iron content; rinsing and draining frozen berries removes some water, so weight-based values can differ from the package weight. For most people, the simplest approach is to track blackberries as part of a varied diet rather than expect them to be a primary iron source.
Daily Iron Targets: Why They Differ
Iron needs vary by life stage and sex. The FDA Daily Value of 18 mg is used on food labels as a general reference, but clinical recommendations differ:
- Adult men and postmenopausal women: about 8 mg per day
- Adult women aged 19–50: about 18 mg per day
- Pregnancy: about 27 mg per day
- Children 1–3 years: 7 mg; children 4–8 years: 10 mg
- Teen girls (14–18): 15 mg; teen boys: 11 mg
These figures are based on the National Institutes of Health Office of Dietary Supplements iron fact sheet. The calculator lets you choose the target most relevant to you, so the percentage is personalized rather than locked to a single label value. You can read the full guidance at the NIH Iron Health Professional fact sheet.
Frequently Asked Questions
How much iron is in 100 g of blackberries? Raw blackberries contain about 0.62 mg of iron per 100 g, which is roughly 3.4% of the FDA Daily Value.
Are blackberries a good iron source? They are not particularly high in iron compared with legumes, fortified cereals, or spinach, but they can contribute a useful amount in larger servings and bring other nutrients like vitamin C, manganese, and fiber. In a balanced diet, they are a healthy addition rather than a primary iron fix.
Does frozen blackberry iron differ from fresh? Generally no, if the frozen berries are unsweetened and the weight is measured after thawing without draining. Added sugar or syrup would lower the iron density per 100 g because the sugar adds weight without iron.
Can I use this calculator for blackberry juice or jam? No — the 0.62 mg/100 g value is specific to whole raw blackberries. Juices and jams have different water, sugar, and processing profiles, so their iron values would need separate reference data.