Supplement Dose Calculator
Choose your sex and age to see the official daily target and safe upper limit for 13 common nutrients.
Values are for healthy adults. Children and people with medical conditions have different needs.
| Nutrient | Daily target | Upper limit | Notes |
|---|---|---|---|
| Vitamin D | 600 IU | 4,000 IU | from all sources |
| Magnesium | 320 mg | 350 mg | from supplements only |
| Zinc | 8 mg | 40 mg | from all sources |
| Calcium | 1,000 mg | 2,500 mg | from all sources |
| Iron | 18 mg | 45 mg | from all sources |
| Vitamin C | 75 mg | 2,000 mg | from all sources; smokers need 35 mg more per day |
| Vitamin B12 | 2.4 mcg | Not set | no upper limit set; adults over 50 should get most B12 from supplements or fortified foods |
| Folate | 400 mcg DFE | 1,000 mcg DFE | applies to folic acid from supplements and fortified foods |
| Vitamin A | 700 mcg RAE | 3,000 mcg RAE | applies to preformed vitamin A (retinol), not beta-carotene |
| Vitamin K | 90 mcg (AI) | Not set | no upper limit set; people on warfarin must keep intake consistent |
| Vitamin B6 | 1.3 mg | 100 mg | long-term high doses can cause nerve damage |
| Selenium | 55 mcg | 400 mcg | from all sources |
| Iodine | 150 mcg | 1,100 mcg | from all sources |
Daily target = Recommended Dietary Allowance (RDA), or Adequate Intake (AI) where no RDA exists, and includes food. Source: NIH Office of Dietary Supplements.
Frequently asked questions
What's the difference between the RDA and the upper limit?
The RDA is the daily amount that meets the needs of nearly all healthy people. The upper limit (UL) is the most you can take daily without a likely risk of harm. Aim near the RDA and stay below the UL.
Do these numbers include food?
Yes. The targets cover food, drinks and supplements combined. For most nutrients the upper limit also covers all sources, but for magnesium it applies to supplements only.
Sources
Free tool for education only. It doesn't replace advice from your doctor or pharmacist.