How to convert grams to milligrams
One gram equals 1,000 milligrams, so multiply the number of grams by 1,000:
mg = g × 1,000
g = mg ÷ 1,000 (1 mg = 0.001 g)
Example: 0.5 g → 0.5 × 1,000 = 500 mg.
Going the other way, divide by 1,000, or multiply by 0.001; the milligrams to grams converter does it for you.
Everyday values
| Grams | Milligrams | For example |
|---|---|---|
| 0.5 g | 500 mg | 500 mg |
| 1 g | 1,000 mg | one gram |
| 2.3 g | 2,300 mg | 2.3 g of sodium, a common daily limit |
| 5 g | 5,000 mg | a teaspoon of salt, roughly |
When you need this conversion
Multiply grams by 1,000. Nutrition labels sometimes show sodium in grams and sometimes in milligrams; 2.3 g is 2,300 mg, a daily sodium limit recommended in US dietary guidelines.
Gram to milligram conversion table
| g | mg | g | mg |
|---|---|---|---|
| 0.1 g | 100 mg | 1.3 g | 1,300 mg |
| 0.2 g | 200 mg | 1.4 g | 1,400 mg |
| 0.3 g | 300 mg | 1.5 g | 1,500 mg |
| 0.4 g | 400 mg | 1.6 g | 1,600 mg |
| 0.5 g | 500 mg | 1.7 g | 1,700 mg |
| 0.6 g | 600 mg | 1.8 g | 1,800 mg |
| 0.7 g | 700 mg | 1.9 g | 1,900 mg |
| 0.8 g | 800 mg | 2 g | 2,000 mg |
| 0.9 g | 900 mg | 2.1 g | 2,100 mg |
| 1 g | 1,000 mg | 2.2 g | 2,200 mg |
| 1.1 g | 1,100 mg | 2.3 g | 2,300 mg |
| 1.2 g | 1,200 mg | 2.4 g | 2,400 mg |
About the units
- Gram (g): one thousandth of a kilogram.
- Milligram (mg): one thousandth of a gram.
Both are units of weight (mass). The conversion factor comes from the exact definitions above, so the calculator is exact; results are only rounded for display (up to six significant digits).
Frequently asked questions
How many milligrams are in one gram?
One gram is 1,000 milligrams. One milligram is 0.001 grams.
How do I convert grams to milligrams?
Multiply the value in grams by 1,000. To go back, divide by 1,000.
What is 0.5 g in milligrams?
0.5 g = 500 mg.
What is 2.3 g in milligrams?
2.3 g = 2,300 mg.
Sources
- NIST Special Publication 811 (2008), Guide for the Use of the International System of Units (SI), Appendix B: conversion factors.
- NIST Handbook 44 (2024), Appendix C: General tables of units of measurement.
Last reviewed 5 October 2026. Results are estimates; see our disclaimer.