Convert Grays to Milligrays (Gy to mGy)
1 gray (Gy) = 1000 milligrays (mGy). 1 mGy = 0.001 Gy. Example: 15 Gy = 15 × 1000 = 15000 mGy.
Also searched as grays to mGy, grays in mGy, grays into milligrays, Gy to mGy, Gy in milligrays, Gy into milligray, gray to milligray, Gy to milligrays converter and how many milligrays in a gray.
1 Gy = 1000 mGy
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk gray to milligray converter to paste a column from Excel.
How to Convert Gray to Milligray
- 1 Gy = 1000 mGy
- 1 mGy = 0.001 Gy
- Example: convert 15 Gy to mGy: 15 Gy = 15 × 1000 mGy = 15000 mGy
Formula
mGy = Gy × 1000
Derivation from SI units:
- 1 Gy = 1 J of absorbed energy per kg.
- 1 mGy = 10⁻³ Gy.
Both units are defined exactly, so the factor is exact. Gray definition: gray; Milligray definition: milligray.
Worked examples
- A reading of 0.5 Gy converts to 500 mGy.
0.5 Gy × 1000 = 500 mGy - A value of 5 Gy is 5000 mGy.
5 Gy × 1000 = 5000 mGy
Gray to Milligray conversion table
| Grays (Gy) | Milligrays (mGy) |
|---|---|
| 0.001 Gy | 1 mGy |
| 0.01 Gy | 10 mGy |
| 0.1 Gy | 100 mGy |
| 0.5 Gy | 500 mGy |
| 1 Gy | 1000 mGy |
| 2 Gy | 2000 mGy |
| 5 Gy | 5000 mGy |
| 10 Gy | 10000 mGy |
| 50 Gy | 50000 mGy |
| 100 Gy | 100000 mGy |
Where it's used
Grays are used for radiotherapy prescriptions, while milligrays appear in CT dose index (CTDIvol). Both measure absorbed dose of ionising radiation, so the conversion is a fixed factor.
Gray to other absorbed dose units
| Conversion | 1 Gy equals |
|---|---|
| gray to milligray | 1000 mGy |
| gray to rad | 100 rad |
| gray to microgray | 1000000 µGy |
| gray to centigray | 100 cGy |
| gray to kilogray | 0.001 kGy |
| gray to millirad | 100000 mrad |
Frequently asked questions
How many milligrays are in 1 gray?
1 Gy = 1000 mGy.
How do I convert grays to milligrays?
Multiply the value in Gy by 1000. For example, 15 Gy × 1000 = 15000 mGy.
Is the Gy to mGy conversion exact?
Yes. Both units are defined exactly, and 1 Gy is exactly 1000 mGy.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4 (becquerel, gray, sievert, lux) and Table 2 (candela).
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Grays to Milligrays (Gy to mGy). Retrieved October 25, 2026, from https://scientificconverters.com/absorbed-dose/grays-to-milligrays/
IEEE
Scientific Converters, "Convert Grays to Milligrays (Gy to mGy)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/absorbed-dose/grays-to-milligrays/