Vitamin D Intake Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/8/2026
The percentage of recommended vitamin D intake is calculated with (vitamin D consumed ÷ reference value) × 100. The reference value is 15 µg/day for an adult and 20 µg/day after age 75; with 10 µg consumed, an adult reaches about 67% of their target.
Explanation
Vitamin D plays an essential role in calcium absorption and bone health, as well as in immune system function. The reference intake set by the French agency ANSES is 15 micrograms per day (600 IU, international units) for a healthy adult, rising to 20 µg/day (800 IU) after age 75, an age at which the skin's capacity to synthesize vitamin D from sunlight declines. A distinctive feature of this vitamin compared with other nutrients covered on this site: diet is only one source among others, and generally not the main one for most people. Skin exposure to UVB rays from the sun triggers a cutaneous synthesis of vitamin D that covers, for many sufficiently exposed people, a substantial share of their needs, particularly in summer. This synthesis varies enormously, however, depending on latitude, season, skin pigmentation, age, and time spent outdoors with exposed skin, which explains why vitamin D deficiency remains common, especially in winter and in regions with low sunlight. The richest dietary sources remain fatty fish (salmon, mackerel, sardine), egg yolk, and certain fortified products (plant-based milks, margarines). This calculator only accounts for declared dietary intake, not cutaneous synthesis, and therefore likely underestimates the real total intake for someone regularly exposed to sunlight. For another micronutrient with sometimes insufficient intake, see our calcium intake calculator, which works in direct synergy with vitamin D for bone health.
Example: a 40-year-old adult, 10 µg of vitamin D consumed
Inputs
Vitamin D consumed: 10 µg. Age: 40 (target 15 µg/day).
Calculation
Percentage of target = (10 ÷ 15) × 100 ≈ 66.67%.
Result
This intake covers about 67% of the recommended vitamin D intake for this profile.
Frequently asked questions
Why does the vitamin D reference value increase after age 75?
Because the skin's ability to synthesize vitamin D from sunlight declines with age, and older people are often less exposed to the sun (reduced mobility, more time spent indoors). The higher reference value after age 75 (20 µg/day versus 15 µg/day) partly compensates for this reduced cutaneous synthesis through greater dietary intake or supplementation.
Does this calculator account for vitamin D produced by sun exposure?
No, it only counts declared dietary intake. For many people sufficiently exposed to the sun, particularly in summer, cutaneous synthesis can cover a substantial share, or even the majority, of actual needs — this calculator therefore likely underestimates total intake for these people, and gives a more accurate picture for people with little sun exposure (winter, indoors, heavily covered skin).
Can you consume too much vitamin D?
Yes, unlike cutaneous synthesis (which naturally self-regulates), excessive intake through supplementation can be dangerous: the European Food Safety Authority (EFSA) sets a safety limit of 100 µg per day for adults, beyond which a risk of hypercalcemia exists. This limit is far higher than the reference value (15-20 µg/day): accidentally exceeding it through diet alone remains unlikely, the risk mainly concerning poorly dosed supplementation, best discussed with a healthcare professional.