Wondering how much iron is in that mackerel fillet? This Mackerel Iron Calculator converts your portion size into a milligram estimate in seconds. Choose the form of mackerel you plan to eat — fresh Atlantic, king, canned in water or oil, or smoked — enter your serving as grams, ounces, fillets, or drained cans, and press calculate. You'll get total iron, the iron density per 100 g, and an optional Daily Value percentage based on the 18 mg adult reference value.
Iron plays a central role in oxygen transport, energy metabolism, and immune health. Mackerel is often celebrated for omega-3s, but it also supplies a meaningful amount of highly absorbable heme iron. This tool is handy for athletes, women with higher iron needs, and anyone using a food diary to reach a micronutrient target. Pair it with other nutrient trackers to build a more complete picture of your daily intake.
🐟 Mackerel Iron Calculator
How to Use This Tool
Using the calculator takes only a few steps. First, choose the mackerel form that matches what you're actually eating — fresh cooked Atlantic mackerel, canned mackerel packed in water or oil, smoked mackerel, or king mackerel. Each form has its own iron density per 100 grams, so picking the right one matters for accuracy.
Next, enter your serving size and choose the matching unit. You can type the amount in grams or ounces, or use the "fillet" and "can" units, which automatically apply standard reference weights: one cooked fillet ≈ 85 g and one drained can ≈ 110 g. If you know the exact weight of your portion, entering it in grams gives the most reliable result.
Finally, press Calculate Iron. The result panel shows the total iron in your serving, the iron density per 100 g, the converted serving weight, and — if the checkbox is on — your percentage of the 18 mg Daily Value for adults. Use the reset button to clear the result and start over.
Use the preset buttons (1 fillet, 100 g, 1 can, 150 g) to instantly test typical serving sizes. They're a great way to see how your usual portion compares to a standard reference serving.
How the Calculation Works
The tool uses a simple two-step formula. First, your serving is converted to grams using these standard conversions:
- 1 ounce = 28.3495 g
- 1 mackerel fillet ≈ 85 g (cooked)
- 1 drained can of mackerel ≈ 110 g
Then total iron is calculated as:
Iron (mg) = serving weight (g) × iron per 100 g ÷ 100
If the Daily Value option is enabled, the result is divided by the 18 mg adult reference value and multiplied by 100 to express it as a percentage. This is the same Daily Value used on Nutrition Facts labels in the United States.
Reference Values Used
The iron densities below are averages drawn from standard food-composition databases (such as USDA FoodData Central) for commonly eaten mackerel forms:
| Mackerel form | Iron per 100 g |
|---|---|
| Fresh Atlantic mackerel, cooked | 1.57 mg |
| Canned mackerel in water, drained | 1.65 mg |
| Canned mackerel in oil, drained | 1.30 mg |
| Smoked mackerel | 1.80 mg |
| King mackerel, cooked | 1.45 mg |
Smoked mackerel tends to show the highest value on this list because smoking removes moisture, concentrating nutrients per 100 g. Canned mackerel packed in oil sits at the lower end because some of the weight measured is absorbed oil rather than fish tissue.
Worked Examples
Example 1 — Atlantic mackerel fillet. A typical cooked fillet weighs about 85 g. Iron = 85 × 1.57 ÷ 100 = 1.33 mg, which is about 7.4% of the Daily Value.
Example 2 — Canned mackerel, drained. One drained can (110 g) of mackerel packed in water gives 110 × 1.65 ÷ 100 = 1.82 mg, about 10.1% of the DV. The same can packed in oil gives 110 × 1.30 ÷ 100 = 1.43 mg, about 7.9% of the DV.
Example 3 — Smoked mackerel fillet. A 120 g smoked portion delivers 120 × 1.80 ÷ 100 = 2.16 mg, about 12.0% of the DV. That's a meaningful contribution for someone tracking iron intake.
Common Questions
Is mackerel a good source of iron? Mackerel is a moderate iron source. A 100 g serving provides roughly 7–9% of the adult Daily Value, which is comparable to many other oily fish but lower than red meat or organ meat. Where mackerel truly shines is its combination of iron with omega-3 fatty acids and vitamin B12.
Is mackerel iron easy to absorb? Yes. Mackerel contains heme iron, the form found in muscle tissue of animals, which is absorbed roughly two to three times more efficiently than non-heme iron from plants. This makes mackerel a useful iron contributor even though the milligram numbers are modest.
Why is the value different for canned fish packed in oil? When mackerel is canned in oil, some oil is absorbed into the flesh. The drained weight per 100 g therefore includes a little oil, slightly lowering the measured iron density compared with fish canned in water or fresh cooked fish.
Should I weigh my fish before or after cooking? The reference values apply to the cooked (or drained) form, so weigh your portion after cooking. Raw mackerel contains more water; if you weigh it raw, the iron estimate will be overstated because water weight inflates the portion size.
Tips for Accurate Tracking
- Weigh fish after cooking and after draining any liquid from the can for the closest estimate.
- Use grams rather than fillets or cans when you can, since individual fillets and can fill levels vary.
- Be consistent: log the same form of mackerel the same way each time so your food diary stays comparable day to day.
- Remember that iron needs vary — adult women generally need more iron than men, so the 18 mg DV is a general reference, not a personal target.
Factors Affecting Accuracy
The values used here are averages from food-composition databases. Actual iron content can vary with fish species, diet, season, fat content, cooking method, and canning brine. Treat all results as reasonable estimates for planning purposes, not laboratory-accurate measurements. For clinical questions about iron deficiency or supplementation, consult a registered dietitian or physician.