How much vitamin D do I need daily?

The NHS recommends 10 micrograms (400 IU) of vitamin D daily for everyone aged 1 and over, especially during autumn and winter (October to March) when sunlight in the UK is insufficient for the body to produce vitamin D.

Can I get enough vitamin D from sunlight alone in the UK?

During spring and summer (April to September), most people in the UK can make enough vitamin D from short periods of sun exposure (around 10-15 minutes of midday sun on bare skin). However, from October to March, the sun is too low for the body to produce vitamin D, and a supplement is recommended.

What happens if I do not get enough vitamin D?

Vitamin D deficiency can lead to bone and muscle problems. In children, severe deficiency can cause rickets. In adults, it can cause osteomalacia, leading to bone pain and muscle weakness. The NHS notes that certain groups are at higher risk, including people who spend little time outdoors, those with darker skin, and people who cover most of their skin.

Can you take too much vitamin D?

Yes. Taking too many vitamin D supplements over a long period can cause excess calcium to build up in the body (hypercalcaemia), which can weaken bones and damage the kidneys and heart. The NHS advises not to take more than 100 micrograms (4,000 IU) per day.

Vitamin D Calculator

Calculate your daily vitamin D intake from supplements, diet, and sun exposure and compare to NHS recommendations

Published by UltraCalculatorsLast reviewed: 26 Mar 2026v1.0Sources:NHS vitamin D NICE vitamin D guidanceEditorial PolicyEstimates only. Always consult a qualified professional.Report an issue

This calculator is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.

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Vitamin D is essential for healthy bones, teeth, and muscles. It helps the body absorb calcium and phosphorus, and plays a role in immune function. Unlike most vitamins, vitamin D can be produced by the body when the skin is exposed to sunlight, which is why it is sometimes called the "sunshine vitamin". However, in the UK, sunlight is only strong enough for the body to make vitamin D between approximately April and September. The NHS recommends that everyone in the UK should consider taking a daily supplement containing 10 micrograms (400 IU) of vitamin D, particularly during autumn and winter when there is not enough sunlight for the body to produce it. Certain groups are advised to take a supplement all year round, including people who are rarely outdoors, those who cover most of their skin, and people with dark skin, as melanin reduces the skin's ability to produce vitamin D from sunlight. This calculator estimates your total daily vitamin D intake from three sources: supplements, dietary intake, and sun exposure. It compares your total intake to the NHS recommended level and provides guidance based on the current season and your skin type. Vitamin D deficiency is common in the UK, with Public Health England estimating that around 1 in 5 people have low vitamin D levels.

How to Use This Calculator

To estimate your daily vitamin D intake: 1. Enter your supplement dose in International Units (IU). Common supplement doses are 400 IU (10mcg), 1000 IU (25mcg), and 4000 IU (100mcg). Check the label on your supplement for the exact dose. 2. Enter your estimated dietary vitamin D intake in IU. Good dietary sources include oily fish (salmon, mackerel, sardines), egg yolks, fortified foods (some breakfast cereals, margarine, plant milks), and red meat. A portion of oily fish can provide around 400 IU. 3. Enter your daily sun exposure in minutes. This should be time spent outdoors with some skin exposed (face and forearms as a minimum). Indoor sun exposure through glass does not count. 4. Select your skin type. Fair skin produces vitamin D more quickly from sunlight, while darker skin requires more time. This affects the sun exposure calculation. 5. Select the current season. During autumn and winter in the UK, the sun is too low in the sky for the body to produce meaningful amounts of vitamin D, regardless of time spent outdoors. 6. Review your results. The calculator shows your total estimated intake in both micrograms and IU, a breakdown by source, your status relative to NHS recommendations, and seasonal advice.

How It Works

The calculator converts all vitamin D sources to micrograms (mcg) for comparison with the NHS recommendation of 10mcg per day. Supplement and dietary contributions are converted from IU to mcg by dividing by 40 (1 mcg = 40 IU). Sun-derived vitamin D is estimated based on skin type and season. During UK spring and summer, the body can produce approximately: 1000 IU per 15 minutes for fair skin, 700 IU per 15 minutes for medium skin, and 400 IU per 15 minutes for dark skin. During autumn and winter, sun contribution is negligible in the UK due to the low angle of the sun. Total intake = supplement (mcg) + dietary (mcg) + sun-derived (mcg). Status categories: below 10mcg is "Deficient", 10-20mcg is "Insufficient" (meets minimum but not optimal), 20-50mcg is "Sufficient", and above 100mcg is "Potentially excessive". The NHS advises against taking more than 100mcg (4,000 IU) per day unless recommended by a doctor.

Vitamin D recommendations are based on SACN (Scientific Advisory Committee on Nutrition) 2016 report, which led to the NHS recommendation of 10mcg daily for the UK population. The sun exposure estimates are approximate and vary based on latitude, time of day, cloud cover, and the amount of skin exposed. Vitamin D is stored in the body's fat tissue, so blood levels reflect intake over weeks and months rather than a single day. A blood test measuring 25-hydroxyvitamin D is the most reliable way to assess vitamin D status. The NHS defines deficiency as below 25 nmol/L. Certain medical conditions, medications, and dietary factors can affect vitamin D absorption and metabolism. If you are concerned about your vitamin D levels, consult your GP. Sources: NHS vitamin D guidance, SACN Vitamin D and Health report (2016), Public Health England PHE and NICE vitamin D guidelines, British Nutrition Foundation.