The drug unit converter converts between the metric units used in drug prescriptions and pharmacology: grams (g), milligrams (mg), micrograms (mcg/μg), and nanograms (ng). Unit confusion — particularly between milligrams and micrograms — is one of the most common and dangerous sources of medication errors, representing a 1000-fold dosing difference. Use this converter to verify unit conversions before drawing up any medication.
| From | To | Multiply by |
|---|---|---|
| g | mg | × 1,000 |
| mg | mcg | × 1,000 |
| mcg | ng | × 1,000 |
| mg | g | ÷ 1,000 |
| mcg | mg | ÷ 1,000 |
| kg | lb | × 2.20462 |
| lb | kg | ÷ 2.20462 |
To convert mg to mcg, multiply by 1,000. The most commonly prescribed strengths are shown below.
| Milligrams (mg) | Micrograms (mcg) |
|---|---|
| 0.05 mg | 50 mcg |
| 0.1 mg | 100 mcg |
| 0.125 mg | 125 mcg |
| 0.2 mg | 200 mcg |
| 0.25 mg | 250 mcg |
| 0.5 mg | 500 mcg |
| 0.75 mg | 750 mcg |
| 1 mg | 1,000 mcg |
| 1.5 mg | 1,500 mcg |
| 2 mg | 2,000 mcg |
| 2.5 mg | 2,500 mcg |
| 5 mg | 5,000 mcg |
| 10 mg | 10,000 mcg |
To convert mcg to mg, divide by 1,000.
| Micrograms (mcg) | Milligrams (mg) |
|---|---|
| 25 mcg | 0.025 mg |
| 50 mcg | 0.05 mg |
| 100 mcg | 0.1 mg |
| 125 mcg | 0.125 mg |
| 200 mcg | 0.2 mg |
| 250 mcg | 0.25 mg |
| 400 mcg | 0.4 mg |
| 500 mcg | 0.5 mg |
| 750 mcg | 0.75 mg |
| 1,000 mcg | 1 mg |
Unit equivalents for strengths often written on labels and orders. This is a unit-conversion reference only — always dose exactly as prescribed and verify against the label.
| Written as | Same as |
|---|---|
| 0.125 mg | 125 mcg |
| 0.25 mg | 250 mcg |
| 0.05 mg | 50 mcg |
| 0.1 mg | 100 mcg |
| 1 mg | 1,000 mcg |
| 500 mg | 0.5 g |
| 1,000 mg | 1 g |
| 250 mg | 0.25 g |
Milliequivalents (mEq) cannot be converted to milligrams with a single factor — the value depends on the specific salt and its molecular weight. Below are the standard equivalents for the IV electrolyte salts nurses handle most often.
| Salt | 1 gram provides | 1 mEq equals |
|---|---|---|
| Potassium chloride (KCl) | ≈ 13.4 mEq K⁺ | ≈ 74.6 mg |
| Sodium chloride (NaCl) | ≈ 17.1 mEq Na⁺ | ≈ 58.4 mg |
| Sodium bicarbonate (NaHCO₃) | ≈ 11.9 mEq | ≈ 84 mg |
| Magnesium sulfate (MgSO₄·7H₂O) | ≈ 8.1 mEq Mg²⁺ | ≈ 123 mg |
| Calcium gluconate | ≈ 4.65 mEq Ca²⁺ | ≈ 215 mg |
There are 1,000 micrograms (mcg) in 1 milligram (mg). This is one of the most important conversions in nursing — mistaking mg for mcg results in a 1000-fold overdose. Always double-check the unit on the drug label before administration.
There are 1,000 milligrams (mg) in 1 gram (g). The full metric chain is: 1 g = 1,000 mg = 1,000,000 mcg = 1,000,000,000 ng.
0.5 mg equals 500 mcg. To convert milligrams to micrograms, multiply by 1,000: 0.5 × 1,000 = 500 mcg. Common examples: 0.25 mg = 250 mcg, and 0.125 mg = 125 mcg (a typical digoxin dose).
No. International units (IU or "units") measure biological activity, not mass, so they cannot be converted to milligrams with a fixed factor. The relationship is drug-specific — insulin units and heparin units each have their own definition. Always dose these medications in units, exactly as prescribed, and never substitute a mg value.