Iron Intake Calculator

Iron is an essential mineral that plays a critical role in producing haemoglobin, the protein in red blood cells that carries oxygen around the body. Iron deficiency is one of the most common nutritional deficiencies worldwide, and the NHS estimates that it affects around 1 in 8 women in the UK. Symptoms of iron deficiency anaemia include fatigue, shortness of breath, pale skin, and difficulty concentrating. The amount of iron you need each day depends on your age, sex, and individual circumstances. Menstruating women need significantly more iron than men due to blood loss during periods, and pregnant women have increased requirements to support the developing baby. Vegetarians and vegans also need to pay closer attention to their iron intake, because plant-based (non-heme) iron is absorbed less efficiently by the body than iron from animal sources (heme iron). This calculator assesses your estimated daily iron intake against the NHS Reference Nutrient Intake (RNI) for your demographic group. It takes into account your age, sex, menstruation status, pregnancy, and whether you follow a vegetarian or vegan diet, and provides a clear assessment of whether you are meeting your recommended intake.

How to Use This Calculator

To assess your daily iron intake: 1. Enter your estimated daily iron intake in milligrams (mg). You can find iron content on food labels or use the NHS food composition database. For reference, a portion of red meat provides about 3-4mg, a bowl of fortified cereal about 3-5mg, and a portion of lentils about 3mg. 2. Enter your age in years. Iron requirements vary by age group, with different targets for children, adolescents, and adults. 3. Select your sex. Men and women have different iron requirements, particularly during reproductive years. 4. If applicable, toggle the menstruation option. Menstruating women aged 19-49 have a higher recommended intake of 14.8mg per day compared to 8.7mg for men and post-menopausal women. 5. If applicable, toggle the pregnancy option. Pregnant women have a recommended intake of 14.8mg per day. 6. If you follow a vegetarian or vegan diet, toggle the vegetarian option. This applies a 1.8x multiplier to the recommended intake, as non-heme iron from plant sources is absorbed approximately 55 percent less efficiently than heme iron from animal sources. 7. Review your results. The calculator shows your intake compared to the recommended amount, a percentage score, and whether you are below, meeting, or exceeding the target.

How It Works

The calculator uses NHS Reference Nutrient Intake (RNI) values to determine the appropriate iron target for your demographic: Men aged 19 and over: 8.7mg per day Women aged 19-49 (menstruating): 14.8mg per day Women aged 50 and over: 8.7mg per day Pregnant women: 14.8mg per day Adolescents aged 11-18: 11.3mg (males), 14.8mg (females) Children aged 7-10: 8.7mg per day Children aged 4-6: 6.1mg per day Children aged 1-3: 6.9mg per day For vegetarians and vegans, the recommended intake is multiplied by 1.8 to account for the lower bioavailability of non-heme iron from plant sources. This factor is based on guidance from the Institute of Medicine and is widely used in clinical nutrition. Percentage of RNI = (your intake / recommended intake) x 100. Values below 100 percent indicate a shortfall, while values at or above 100 percent indicate the target is being met.

Iron absorption can be significantly influenced by other dietary factors. Vitamin C (ascorbic acid) enhances non-heme iron absorption and is recommended alongside plant-based iron sources. Conversely, tannins in tea and coffee, calcium in dairy products, and phytates in wholegrains can inhibit iron absorption. Iron supplements should only be taken on the advice of a GP or healthcare professional, as excess iron can be harmful. The NHS advises that most people should be able to get all the iron they need from a varied and balanced diet. Iron-rich foods include: red meat, liver (avoid during pregnancy due to vitamin A content), pulses (beans, lentils, chickpeas), tofu, fortified breakfast cereals, dark green leafy vegetables (spinach, kale, broccoli), dried fruits (apricots, raisins), nuts, and wholemeal bread. Sources: NHS iron guidance, British Dietetic Association iron fact sheet, SACN dietary reference values, Institute of Medicine bioavailability factors.