Vitamin Calculator — Daily Vitamin Needs by Age & Sex
Find the NIH Recommended Dietary Allowances (RDAs) for eight key vitamins — A, C, D, E, K, B6, B12 and folate — based on your age and sex.
Sex
years
8 vitamins
trackedFat-soluble (A, D, E, K)
50%
Water-soluble (C, B-group)
50%
How does this calculator work?
There is no single calculation — vitamin RDAs are evidence-based reference values set by the National Academies. For most adult men and women, key daily targets include vitamin A (900/700 mcg RAE), C (90/75 mg), D (600–800 IU), E (15 mg) and B12 (2.4 mcg). Needs shift slightly with age and differ by sex for some vitamins.
Formula
How this is calculated
The Recommended Dietary Allowance (RDA) is the average daily intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a particular life stage and sex group. These values are established by the Institute of Medicine (National Academies) and published by the NIH Office of Dietary Supplements. They are updated periodically as new evidence emerges — the values shown here are current as of 2024.
For most vitamins, the RDA is the same for both sexes throughout adulthood, but there are notable exceptions: vitamin A (900 vs 700 mcg RAE), vitamin K (120 vs 90 mcg), and vitamin B6 (1.7 vs 1.5 mg after age 50) differ by sex. Vitamin D increases from 600 to 800 IU for adults over 70 because absorption efficiency declines with age.
These are population-level reference intakes, not personalised prescriptions. Individual needs vary with health conditions, medications, pregnancy, dietary patterns (especially for B12 in vegans) and sun exposure (especially for vitamin D). Always consult a healthcare professional before starting high-dose supplementation, particularly for fat-soluble vitamins A, D, E and K, which accumulate in the body and can reach harmful levels.
Frequently asked questions
The RDA is the intake that meets the needs of nearly all healthy people. The Tolerable Upper Intake Level (UL) is the maximum daily intake unlikely to cause harm — regular intake above the UL carries increasing risk of adverse effects. This calculator shows RDAs only.
Most people who eat a varied diet meet their RDAs through food alone. Supplements are commonly recommended for vitamin D (in low-sunlight regions), B12 (for vegans and older adults), and folate (before and during pregnancy). Discuss your specific needs with a doctor.
The intestinal absorption of vitamin D and the efficiency of skin synthesis both decline with age, so older adults need more dietary vitamin D (800 IU vs 600 IU) to achieve the same serum level.
Also known as
TG we-Calculate Editorial Team. (2026). Vitamin Calculator — Daily Vitamin Needs by Age & Sex [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/vitamin-calculator
TG we-Calculate Editorial Team. "Vitamin Calculator — Daily Vitamin Needs by Age & Sex." TG we-Calculate. 2026. https://we-calculate.com/calculator/vitamin-calculator.
TG we-Calculate Editorial Team, "Vitamin Calculator — Daily Vitamin Needs by Age & Sex," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/vitamin-calculator
@misc{wecalculate_vitamin_calculator, title = {Vitamin Calculator — Daily Vitamin Needs by Age & Sex}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/vitamin-calculator}}, year = {2026}, note = {TG we-Calculate} }
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