Iron Intake Calculator

Iron intake is the amount of iron you eat and drink in a day, measured in milligrams (mg). Your body needs iron to make hemoglobin, the protein in red blood cells that carries oxygen. This calculator looks up your daily target and upper limit, then adds up the iron in the foods you enter.

What Iron Intake Measures

It measures how much iron is in your food, not how much your body absorbs or stores. Only a blood test can show whether you are low in iron or have anemia¹ ⁵.

The Formula

Daily target = RDA for your age, sex and life stage

Vegetarian target = RDA x 1.8

Total iron (mg) = sum of (servings x mg per serving) + other iron from labels

The targets and upper limits come from the NIH Office of Dietary Supplements (ODS), which notes that iron needs are 1.8 times higher for people who eat a vegetarian diet¹.

How This Calculator Computes Your Result

Enter your age and sex. Women aged 14 to 50 can choose pregnant or breastfeeding. Turn on the vegetarian toggle if you eat no meat, poultry or seafood, and the target is multiplied by 1.8.

Then enter servings per day for the foods you ate, split into meat, poultry and seafood (which contain heme iron) and plant foods, eggs and fortified foods (non-heme iron only). Iron values per serving come from the ODS food table, which uses USDA FoodData Central data¹. For breakfast cereal, enter the % Daily Value for iron from the label (100% equals 18 mg)¹. You can also add iron from other labels, including supplements, in mg.

The result shows your target, your upper limit, and your total (to one decimal) as a percent of the target.

For example, a 30-year-old woman who eats a cereal with 25% DV, 3 ounces of chicken, half a cup of spinach, 2 slices of whole wheat bread and an egg gets about 11.5 mg. That is 64% of her 18 mg target.

What Your Result Means

These are the daily targets (Recommended Dietary Allowances, or RDAs) and upper limits (ULs) in mg per day¹:

The value for babies up to 6 months is an Adequate Intake, based on the iron healthy breastfed babies get¹. For vegetarians, the 1.8 factor turns 18 mg into 32.4 mg for women aged 19 to 50, and 8 mg into 14.4 mg for adult men.

Your result falls into one of three bands:

The RDA is set to cover nearly all (97% to 98%) healthy people¹. So being under it does not mean you are deficient. The upper limit counts food, drinks and supplements together². It is set to avoid side effects such as stomach upset, and doctors sometimes prescribe more to treat iron deficiency¹.

Iron supplements in tablet or capsule form must carry this FDA label warning: "Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6."³ The same label also says to keep the product out of reach of children³.

Heme and Non-Heme Iron in Common Foods

Heme iron is found in meat, poultry and seafood. Non-heme iron is found in plants, eggs and fortified foods, and also in meat. Heme iron is absorbed better than non-heme iron¹. Here are some common sources from the ODS table¹:

Dairy foods such as milk and cheese are poor sources, with close to 0 mg per serving¹.

What Helps and Hurts Iron Absorption

Vitamin C helps your body take in non-heme iron¹. Foods such as citrus fruits, strawberries, sweet peppers, tomatoes and broccoli can help when eaten with plant sources of iron². Eating meat, poultry or seafood in the same meal also helps¹.

Some foods work the other way. Phytates in grains and beans and some polyphenols in plants reduce non-heme iron absorption¹. In one study, black tea served with a meal cut non-heme iron absorption by 79% to 94%, and coffee and herb teas were also strong inhibitors⁴. Calcium may reduce absorption too, so ODS suggests taking calcium and iron supplements at different times of day¹ ².

Overall, people absorb about 14% to 18% of the iron in mixed diets that include meat, and about 5% to 12% from vegetarian diets¹. This gap is why the vegetarian target is higher.

Who Is Most at Risk of Low Iron

ODS lists these groups as most likely to have trouble getting enough iron¹ ²:

• Teen girls and women with heavy periods

• Pregnant women and teens, whose blood volume grows

• Infants and young children, especially those born early or at a low birth weight

• Frequent blood donors (about 25% to 35% of regular donors become iron deficient)

• People with cancer, gut disorders such as celiac disease or Crohn's disease, or heart failure

If you are in one of these groups, a food total cannot show your iron status. Doctors check iron with blood tests such as a complete blood count, hemoglobin and ferritin⁵. ODS calls serum ferritin the most efficient test for iron deficiency¹.