# How do I convert mg to ml?

Converts mg to ml and back: mL = mg ÷ concentration (mg/mL).

- Page: https://www.acalculator.org/convert/mg-to-ml
- JSON spec: https://www.acalculator.org/convert/mg-to-ml.json
- Version: 48c00d847791

## Default answer

Example with the default inputs (Milligrams (mg) 1, Concentration (mg/mL) 50): 1 mg = 0.02 ml.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Milligrams (mg) | The amount in mg. |
| mgPerMl | Concentration (mg/mL) | From the label: 250 mg per 5 mL is 50. |
| result | Milliliters (mL) | The same amount in ml. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Milligrams (mg) | The amount in mg. |
| mgPerMl | Concentration (mg/mL) | From the label: 250 mg per 5 mL is 50. |
| result | Milliliters (mL) | The amount in ml. |

## Method

mL = mg ÷ concentration (mg/mL)

## Assumptions

- Exact on the typed decimals: at most 6 decimal places (6 significant digits below 0.0001), rounded half up.

## Worked examples

1. value = 250, mgPerMl = 50 gives result = 5. Source: NIST SP 811 (2008), Appendix B.8: mg and mL.
2. value = 30, mgPerMl = 12 gives result = 2.5. Source: NIST SP 811 (2008), Appendix B.8: mg and mL.

## FAQ

### How do I convert mg to mL?

Divide the milligrams by the concentration in mg per mL: mL = mg ÷ (mg/mL). A milligram measures weight and a milliliter volume, so you need the concentration to link them.

### How many mL is 250 mg?

It depends on the liquid. At 50 mg/mL (250 mg per 5 mL) it is 250 ÷ 50 = 5 mL. At 125 mg/mL it is 2 mL.

### How do I find the concentration on a label that says 250 mg/5 mL?

Divide: 250 ÷ 5 = 50 mg/mL. Enter 50 as the concentration.

### Is 1 mg the same as 1 mL?

Only for a liquid with 1 mg in each mL. For water, 1 mL weighs about 1,000 mg (1 g), so the concentration of water itself is about 1,000 mg/mL.

### Can I use this for a medicine dose?

It does the arithmetic only. Check every dose with a doctor or pharmacist, and measure with an oral syringe or the cup that came with the medicine, not a kitchen spoon.

## Sources

- NIST SP 811 (2008), Guide for the Use of the International System of Units, Table 3 (watt = volt × ampere) and Appendix B.8, retrieved 2026-10-01. https://www.nist.gov/pml/special-publication-811