Convert Grams to Milligrams - Weight Converter
This tool converts a mass value in grams to the equivalent value in milligrams using the International System of Units (SI) relationship between the units. It is intended for quick, precise unit conversion in laboratory, industrial, educational, and everyday contexts.
Conversions are exact when using the standard SI prefix definition. For regulated, safety-critical, or legal measurements (for example, exposure limits, medical dosages, or product labeling), follow instrument calibration procedures and the applicable national or international standards referenced below.
Interactive Converter
Convert between gram and milligram with precision rounding.
Quick reference table
| Gram | Milligram |
|---|---|
| 1 g | 1 mg |
| 5 g | 5 mg |
| 10 g | 10 mg |
| 25 g | 25 mg |
| 50 g | 50 mg |
| 100 g | 100 mg |
Methodology
The conversion relies on the SI prefix milli, which denotes a factor of one thousandth. One gram equals one thousand milligrams.
This is a fixed mathematical relationship and does not require empirical measurement. For measurement results derived from balances or scales, include instrument uncertainty, calibration status, and traceability to national standards when reporting.
For workplace and safety contexts, consult occupational exposure limits and recordkeeping requirements before using converted values for compliance decisions.
Key takeaways
Multiply grams by 1,000 to get milligrams. The mathematical relationship is exact; measurement uncertainty depends on the instrument.
For regulated uses, apply calibration, uncertainty propagation, and consult standards and regulators referenced above before final reporting.
Further resources
Expert Q&A
Is the conversion exact?
Yes. The unit relationship 1 gram = 1,000 milligrams is an exact definition within the International System of Units (SI). Any rounding or uncertainty comes from measurement instruments, not the conversion factor.
Do I need to calibrate my scale before converting?
You should calibrate and verify your weighing instrument according to manufacturer guidance and relevant standards if you rely on the measurement for regulated, clinical, or safety-critical uses. Conversion does not remove instrument bias or drift.
How should I report precision after conversion?
Report the converted value with the same number of significant figures implied by the measurement uncertainty. For example, if a balance reports 2.50 g ±0.01 g, convert both the nominal value and the uncertainty: 2.50 g = 2500 mg and ±0.01 g = ±10 mg.
Are there regulatory rules I should know about?
Yes. For occupational exposure, labeling, medical dosing, or hazardous materials, consult applicable regulations and guidance before using converted values in compliance reporting. Relevant standards bodies and regulators are cited below.
Does conversion change units for concentration calculations?
No. Converting mass units is independent of concentration units. When calculating concentration (for example mg/L), convert mass units first, then apply the volume unit consistently and propagate uncertainties.
Sources & citations
- NIST Metric and SI Resources — https://www.nist.gov/pml/weights-and-measures/metric-si
- ISO Standards on Quantities and Units (ISO) — https://www.iso.org/standard/63555.html
- IEEE Standards Association — https://standards.ieee.org/
- OSHA (Occupational Safety and Health Administration) — https://www.osha.gov/