5,000 IU of vitamin D to mg and mcg

5,000 IU of vitamin D = 125 mcg = 0.125 mg. Vitamin D has 40 IU per microgram, so divide IU by 40 to get mcg and by 40,000 to get mg.

How the conversion works

mcg = IU ÷ 40 → 5,000 ÷ 40 = 125 mcg mg = mcg ÷ 1,000 → 125 ÷ 1,000 = 0.125 mg

The factor comes from the NIH Office of Dietary Supplements: 1 mcg of vitamin D (cholecalciferol, D3, or ergocalciferol, D2) has 40 IU of activity. It works backwards too: 125 mcg × 40 = 5,000 IU.

Where you'll see 5,000 IU

5,000 IU is above the 4,000 IU (100 mcg) daily upper limit NIH sets for adults, so it's normally taken only when a clinician recommends it. Since the FDA's label rules changed (compliance from 2020–2021), supplement labels show vitamin D in mcg, often with IU in brackets: look for 125 mcg (5,000 IU).

This page converts units; it doesn't recommend a dose. NIH sets the adult upper limit at 4,000 IU (100 mcg) a day. Talk to your clinician about what's right for you.

Convert another amount

Nearby doses

• 1,000 IU to mg = 25 mcg
• 2,000 IU to mg = 50 mcg
• 50,000 IU to mg = 1,250 mcg

See every common strength in the vitamin D IU to mcg table, or convert vitamin E, A and insulin with the IU to mg converter.