Pick your sex, age, and life stage to see the recommended daily amount and the safe upper limit for 16 vitamins and minerals — straight from the NIH / National Academies Dietary Reference Intakes — plus the cheapest cost-per-dose deal for each.
Updated June 2026
Sex
Age
Stage
| Nutrient | Recommended / day | Upper limit / day | Best value |
|---|---|---|---|
| Vitamin D | 600 IURDA* | 4,000 IU | cheapest |
| Vitamin C | 75 mgRDA | 2,000 mg | cheapest |
| Vitamin B6 | 1.3 mgRDA | 100 mg | cheapest |
| Folate | 400 mcg DFERDA | 1,000 mcg DFE** | cheapest |
| Vitamin B12 | 2.4 mcgRDA | none set | cheapest |
| Vitamin A | 700 mcg RAERDA | 3,000 mcg RAE*** | cheapest |
| Vitamin E | 15 mgRDA | 1,000 mg | cheapest |
| Vitamin K | 90 mcgAI**** | none set | cheapest |
| Magnesium | 310 mgRDA | 350 mg***** | cheapest |
| Calcium | 1,000 mgRDA | 2,500 mg | cheapest |
| Zinc | 8 mgRDA | 40 mg | cheapest |
| Iron | 18 mgRDA | 45 mg | cheapest |
| Selenium | 55 mcgRDA | 400 mcg | cheapest |
| Iodine | 150 mcgRDA | 1,100 mcg | cheapest |
| Potassium | 2,600 mgAI | none set | cheapest |
| Choline | 425 mgAI | 3,500 mg | cheapest |
RDA = Recommended Dietary Allowance; AI= Adequate Intake (used where there’s no RDA). Figures are general adult references from the NIH Office of Dietary Supplements / National Academies DRIs — not personalised medical advice.
* Vitamin D: Shown in IU — divide by 40 for mcg (600 IU = 15 mcg, 800 IU = 20 mcg).
** Folate: Upper limit is 1,000 mcg of folic acid from supplements/fortified food.
*** Vitamin A: Upper limit is for preformed vitamin A (retinol) only, not beta-carotene.
**** Vitamin K: Adequate Intake for TOTAL vitamin K — no separate reference exists for K2.
***** Magnesium: The 350 mg upper limit is for SUPPLEMENTAL magnesium only — that’s why it sits below the total-intake RDA (food magnesium isn’t counted).
It depends on your sex, age, and whether you’re pregnant or breastfeeding. Pick your profile in the calculator above to see the recommended daily amount (the RDA, or an Adequate Intake where no RDA exists) and the tolerable upper limit for each nutrient, from the NIH / National Academies Dietary Reference Intakes.
The RDA (or AI) is the daily amount that meets most people’s needs. The tolerable upper limit is the most you can take per day without raising the risk of harm. Aim to meet the RDA from food + supplements, and stay at or below the upper limit unless a clinician advises otherwise.
The 350 mg magnesium upper limit applies only to magnesium from supplements, while the recommended amount counts magnesium from all sources including food. So a 400 mg RDA and a 350 mg supplemental upper limit are not a contradiction.