Weights and measures — drug calculations
Unit conversion: mg, micrograms and mL
How to convert between g, mg, micrograms, L, dL and mL, with a table, worked examples and a unit converter.
The units you need to know
Each step is a factor of 1000 for weight. Volume follows the metric system.
| Unit | Equals |
|---|---|
| 1 g | 1000 mg |
| 1 mg | 1000 micrograms |
| 1 microgram | 1000 nanograms |
| 1 L | 10 dL = 1000 mL |
| 1 dL | 100 mL |
How to move the decimal point
Going from a larger unit to a smaller one (g → mg → micrograms), multiply by 1000 for each step. Going the other way, divide by 1000.
0.25 × 1000 = 250 micrograms
2.5 × 1000 = 2500 mg
750 ÷ 100 = 7.5 dL
Unit converter
Choose the type, enter the value and select the units.
Convert between units
Common mistakes
Moving the decimal point the wrong way
Always check whether the answer should be a larger or smaller number. Going from g to mg, the number should get larger.
Mixing units in the same calculation
A dose in mg and a strength in micrograms must first be converted to the same unit before you divide.
Dropping a zero
Do a sense check: is the answer a realistic dose?
Frequently asked questions
How many mg are in 1 g?+
1 g is 1000 mg.
How many micrograms are in 1 mg?+
1 mg is 1000 micrograms.
How do I convert 0.5 mg to micrograms?+
Multiply by 1000: 0.5 × 1000 = 500 micrograms.
Why should micrograms be written out in full?+
The abbreviation can be misread as mg, which is an error by a factor of 1000, so micrograms is always written out in full.
Never slip up on units again
Practise converting mg, micrograms, mL and dL in practice questions, and use the statistics to see where you lose marks. Dos is a practice app for drug calculations, with practice tests of ten questions, a built-in calculator next to each question and statistics per topic.
