# How do I convert kg to mg?

Converts kilograms (kg) to milligrams (mg) and back, with the exact unit definitions.

- Page: https://www.acalculator.org/convert/kg-to-mg
- JSON spec: https://www.acalculator.org/convert/kg-to-mg.json
- Version: 006341b12279

## Default answer

Example with the default inputs (Kilograms (kg) 1): 1 kg = 1,000,000 mg.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Kilograms (kg) | The amount in kilograms to convert. |
| result | Milligrams (mg) | The same amount in milligrams. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Kilograms (kg) | The amount in kilograms to convert. |
| result | Milligrams (mg) | The amount in milligrams. |

## Method

mg = kg × 1000000 (the same as kg ÷ 0.000001)

## Assumptions

- 1 kilogram = 1000000 milligrams, from the exact definitions in NIST SP 811.
- The answer shows at most 6 decimal places; the calculation keeps full precision.

## Worked examples

1. value = 1 gives result = 1,000,000. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
2. value = 0.25 gives result = 250,000. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
3. result = 250,000 gives value = 0.25. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.

## FAQ

### How many milligrams are in a kilogram?

1 kilogram is 1,000,000 milligrams, from the exact unit definitions (NIST SP 811).

### How do I convert kg to mg?

Multiply by 1,000,000: mg = kg × 1000000 (the same as kg ÷ 0.000001). For example, 1 kg × 1,000,000 = 1,000,000 mg.

### How do I convert mg back to kg?

Multiply by 0.000001, or type the milligrams into the second box and the converter works it out. 1 milligram is 0.000001 kilograms.

## Sources

- NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B.8. https://www.nist.gov/pml/special-publication-811