1g = 1,000mg

1mg = 1,000mcg 

1g = 1,000,000mcg

g (grams)

mg (milligram)

mcg (microgram)

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EXAMPLE:

To convert 400 micrograms (mcg) to milligrams (mg), divide by 1000 (since 1 milligram = 1000 micrograms):

400 mcg ÷ 1000 = 0.4 mg

To convert 0.4 milligrams (mg) to grams (g), divide by 1000 (since 1 gram = 1000 milligrams):

0.4 mg ÷ 1000 = 0.0004 g

Therefore, 400mcg is equivalent to 0.4mg or 0.0004g.