How to convert mg to kg
kg = mg × 0.000001. The scale factor is the source-unit factor divided by the destination-unit factor.
Worked example
For a parcel mass or material quantity of 5 mg converts to 0.000005 kg.
- Start with 5 mg.
- Multiply 5 by 0.000001.
- Report 0.000005 kg, rounded to the precision of your original measurement.
Check the reverse conversion
1 kg = 1,000,000 mg. Use the kilogram to milligram converter to calculate in the opposite direction. This has its own formula and reference table.
Definitions that matter
Pounds and ounces here are avoirdupois units, not troy units for precious metals. A tonne is 1,000 kg; it is not a US short ton or imperial long ton. Mass is not gravitational force.
The base unit for this category is kg. One mg corresponds to 0.000001 kg; one kg corresponds to 1 kg. These definitions explain the relationship rather than relying on a rounded display value.
Sources and precision
Definitions: NIST Guide to the SI. Calculations use double precision; the tool defaults to a readable rounded result, while tables show up to ten significant digits. Displaying more digits does not increase the accuracy of the original measurement.
Read our calculation methodology and content standards, or continue with kilograms, pounds and exact conversion factors.