MCG vs MG
Conversion Calculator
Convert between micrograms and milligrams instantly with scientific precision. Built for healthcare professionals, pharmacists, and researchers.
How the Conversion Works
Watch the conversion process flow in real-time as you type
What is a Microgram?
A microgram (mcg or μg) is one millionth of a gram. It is commonly used for precise dosing of vitamins, hormones, and potent medications like folic acid and vitamin D.
What is a Milligram?
A milligram (mg) is one thousandth of a gram. It is the standard unit for most medication dosages, supplements, and nutritional labeling worldwide.
Why Accuracy Matters
In pharmacology, confusing mcg with mg can result in a 1,000× dosage error. Always double-check your conversions, especially for critical medications.
Quick Reference Table
| Micrograms (mcg) | Milligrams (mg) | Common Use |
|---|---|---|
| 1 mcg | 0.001 mg | Vitamin B12 dose |
| 50 mcg | 0.05 mg | Selenium supplement |
| 100 mcg | 0.1 mg | Folic acid (low dose) |
| 200 mcg | 0.2 mg | Chromium picolinate |
| 400 mcg | 0.4 mg | Folic acid (standard) |
| 500 mcg | 0.5 mg | Vitamin B12 (high dose) |
| 1,000 mcg | 1 mg | Melatonin tablet |
| 5,000 mcg | 5 mg | Biotin supplement |
| 10,000 mcg | 10 mg | Iron supplement |
Frequently Asked Questions
To convert micrograms to milligrams, divide the microgram value by 1,000. For example, 500 mcg ÷ 1,000 = 0.5 mg. Our calculator does this instantly as you type.
To convert milligrams to micrograms, multiply the milligram value by 1,000. For example, 2.5 mg × 1,000 = 2,500 mcg. Enter your value in the mg field to see instant results.
Yes, mcg and μg are both abbreviations for microgram. The "mcg" notation is preferred in medical contexts to avoid confusion with "mg" (milligrams), as the Greek letter μ can be misread.
Confusing mcg with mg creates a 1,000-fold dosage error. For potent drugs like digoxin, levothyroxine, or fentanyl, this mistake can be life-threatening. Always verify your unit conversions carefully.
Common substances include vitamin B12, vitamin D, folic acid, selenium, chromium, biotin, levothyroxine, and many hormonal medications. These require precise microgram-level dosing.