Vitamin D Intake Calculator
Calculate your recommended daily vitamin D intake (IU and mcg) based on age, weight, sun exposure, and health goals.
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How to use this calculator
- 1
Enter your age and weight.
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Select how much daily sun exposure you typically get.
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Choose your latitude/location and skin tone.
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Select your health goal or condition.
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Follow the supplement recommendation and take with a fatty meal for best absorption.
Frequently asked questions
How much vitamin D should I take daily?
The RDA is 600 IU for adults under 70 and 800 IU for adults over 70. However, many experts and studies suggest 1000–2000 IU/day is optimal for most adults, especially those with limited sun exposure. The safe upper limit is 4000 IU/day for adults. Doses above 10,000 IU/day long-term risk toxicity. Always get a blood test to determine your actual needs.
What are signs of vitamin D deficiency?
Symptoms of vitamin D deficiency include: fatigue and low energy, bone pain and muscle weakness, frequent infections (colds, flu), depression or low mood, slow wound healing, hair loss, and aches/pains. However, many people with deficiency have no obvious symptoms. A blood test (25-OH vitamin D) is the only reliable way to check your levels.
Can I get enough vitamin D from sunlight?
In theory, 15–30 minutes of midday sun on arms and legs produces 10,000–20,000 IU — far more than daily needs. But many factors reduce this: living above 35° latitude (especially Oct–March), always wearing sunscreen or covering up, being indoors, having darker skin, ageing (older skin synthesises D less efficiently), and smog reducing UV penetration.
What is the difference between vitamin D2 and D3?
Vitamin D3 (cholecalciferol) is the form produced by your skin from sunlight and found in animal-based foods (fatty fish, egg yolks). Vitamin D2 (ergocalciferol) comes from plants and fungi. Both raise blood vitamin D levels, but D3 is more effective and maintains levels longer. Most supplementation guidelines recommend D3.
Free Vitamin D Intake Calculator
The global vitamin D deficiency problem
An estimated 1 billion people worldwide are vitamin D deficient or insufficient. Risk is highest in northern countries (UK, Canada, Scandinavia, northern US), people who stay indoors, those who cover their skin for cultural or religious reasons, people with darker skin tones (more melanin = less UV synthesis), and the elderly. In the UK, the NHS recommends everyone take 400 IU (10mcg) daily in autumn and winter.
Vitamin D and health: what the research says
Vitamin D's established roles: calcium absorption and bone density (deficiency causes rickets in children and osteomalacia in adults), immune function, muscle function. Actively researched associations: reduced risk of respiratory infections, improved mood and depression, possible cancer risk reduction. Supplement during winter months or when you can't get adequate sunlight — the evidence for supplementation in deficient populations is strong.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →