Grapefruit isn't a high-iron food, but when you're tracking micronutrients every milligram counts. A medium pink or red grapefruit contains about 0.18 mg of iron — roughly 1% of the 18 mg Daily Value — while a cup of sections delivers around 0.18 mg. This calculator estimates the iron content for any amount of grapefruit flesh, halves, or juice, measured in grams, ounces, cups, whole fruit, or halves.
Values reflect average USDA-style data for white and pink/red varieties, so the result is a practical estimate rather than a lab measurement. The tool also converts your serving into grams, total iron, and percent Daily Value, and can show an optional estimate of absorbed non-heme iron. If you're pairing grapefruit with leafy greens or beans, the vitamin C note helps you understand how the fruit supports iron absorption from other plant foods in the same meal.
🍊 Grapefruit Iron Calculator
Estimate the iron in any serving of grapefruit flesh, halves, or juice, and see how it compares to the 18 mg Daily Value.
1. Amount
2. Form / variety
Step-by-Step Guide
Using the calculator takes just a few seconds. Start by entering the amount of grapefruit you want to evaluate — you can type any number in the amount field. Next, pick the matching unit from the dropdown: grams, ounces, cups, whole medium fruit, or halves. Then choose the form and variety: pink/red flesh, white flesh, pink/red juice, or white juice. If you'd like to see an absorbed-iron estimate, leave the bioavailability checkbox ticked. Press Calculate, and the result panel shows the converted weight in grams, the iron per 100 g for the selected form, the total iron in your serving, and its percent of the 18 mg Daily Value.
Example: A 1-cup serving of pink/red grapefruit sections weighs about 230 g and contains roughly 0.18 mg iron, which is about 1% of the Daily Value. Doubling to 2 cups brings the total to about 0.37 mg — still small, but meaningful when you are tracking micronutrients across a whole day.
How the Estimate Is Calculated
Iron values for each grapefruit form are expressed as milligrams per 100 grams (mg/100 g), which is the standard way nutrient densities are reported in food composition databases. The calculator first converts your chosen serving to grams using these average equivalents:
- 1 ounce = 28.35 g
- 1 cup of grapefruit sections ≈ 230 g
- 1 cup of grapefruit juice ≈ 248 g
- 1 medium fruit ≈ 230 g of edible flesh
- 1 half fruit ≈ 115 g of edible flesh
Once the serving is expressed in grams, the total iron is calculated with:
Total iron (mg) = grams × iron per 100 g ÷ 100
% Daily Value = total iron ÷ 18 mg × 100
The 18 mg figure is the FDA's Daily Value for iron, used on Nutrition Facts labels. For a 230 g serving of pink flesh (0.08 mg/100 g), the math works out as 230 × 0.08 ÷ 100 = 0.184 mg, then 0.184 ÷ 18 × 100 ≈ 1.0% DV.
Reference Values
The calculator uses the following composite averages, consistent with USDA FoodData Central listings for raw grapefruit and unsweetened juice:
| Grapefruit form | Iron per 100 g | Approx. per 1 cup |
|---|---|---|
| Pink / red flesh | 0.08 mg | 0.18 mg |
| White flesh | 0.05 mg | 0.12 mg |
| Pink / red juice | 0.10 mg | 0.25 mg |
| White juice | 0.10 mg | 0.25 mg |
Variety, ripeness, growing conditions, and how long the fruit has been stored all cause natural variation, so treat the output as a practical estimate rather than a laboratory measurement.
Worked Examples
Example 1 — Half a white grapefruit: A half fruit is about 115 g of flesh at 0.05 mg/100 g. Iron = 115 × 0.05 ÷ 100 = 0.058 mg, about 0.3% DV. That is a very small amount, but it still contributes a little vitamin C to a meal.
Example 2 — 300 g of pink juice: At 0.10 mg/100 g, iron = 300 × 0.10 ÷ 100 = 0.30 mg, about 1.7% DV. Per weight, juice is the highest of the four forms in this calculator.
Example 3 — 4 oz of pink flesh: 4 oz = 113.4 g at 0.08 mg/100 g → 0.09 mg, about 0.5% DV. Using ounces instead of cups is handy when a recipe weighs ingredients or you are using a kitchen scale.
Limitations & Pro Tips
Whole-fruit sizes vary widely. The calculator uses an average edible flesh weight of 230 g per medium fruit (about 10 cm in diameter). If you have a kitchen scale, weigh the fruit and choose grams or ounces for the most accurate result.
- The 18 mg Daily Value is the FDA label reference for adults; the recommendation for pregnant women is higher (27 mg), so adjust the percentages mentally if that applies to you.
- Iron in grapefruit is non-heme iron, and absorption typically ranges from 10–20%, influenced by your body's iron status and the rest of the meal.
- Vitamin C is the standout nutrient here: one medium pink grapefruit delivers about 70–90 mg of vitamin C, which can improve absorption of non-heme iron from plant foods eaten at the same time.
Pair grapefruit with iron-rich plant foods like spinach, lentils, or tofu. The fruit's vitamin C can make more of that iron actually absorbable — a simple way to get more value from a plant-based meal.
Frequently Asked Questions
Is grapefruit a good source of iron?
Not in large amounts — a typical serving supplies about 0.5–2% of the Daily Value. Its real nutritional contribution is vitamin C, water content, and potassium. It is more useful as a mealtime companion that supports iron absorption from other plant foods than as a direct iron source.
Why does the juice value differ from the flesh?
Juice is mostly water and loses some pulp, so its mineral density differs slightly from intact flesh. Canned or bottled juice can also be fortified or diluted, so the calculator uses a separate composite value for juice.
Should I choose pink/red or white grapefruit for iron?
Pink and red varieties contain more beta-carotene and lycopene and tend to be higher in some nutrients; iron differences between the varieties are small. Choose mostly on taste — both work well with iron-rich meals.
Can grapefruit interfere with medications?
Yes. Grapefruit juice can affect enzymes in the liver and intestine that metabolize many medications, including some statins and blood-pressure drugs. If you take prescription medicine, check with your pharmacist or doctor before adding grapefruit to your diet. This calculator is for nutrition education only and is not medical advice.
Additional Resources
Composite nutrient values for this calculator are based on public USDA food data. You can look up the source entries, including analytical methods and sample counts, in USDA FoodData Central:
- USDA FoodData Central — search "grapefruit, raw" or "grapefruit juice" for detailed nutrient profiles.
- NIH Office of Dietary Supplements: Iron fact sheet — background on iron requirements, absorption, and Daily Values.