Convert Rads to Grays (rad to Gy)
1 rad = 0.01 grays (Gy). 1 Gy = 100 rad. Example: 100 rad = 100 × 0.01 = 1 Gy.
Also searched as rad to Gy, rads to grays and rad to gray conversion.
1 rad = 0.01 Gy
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk rad to gray converter to paste a column from Excel.
How to Convert Rad to Gray
- 1 rad = 0.01 Gy
- 1 Gy = 100 rad
- Example: convert 100 rad to Gy: 100 rad = 100 × 0.01 Gy = 1 Gy
Formula
Gy = rad ÷ 100
Derivation from SI units:
- 1 rad = 100 erg/g = 0.01 Gy.
- 1 Gy = 1 J of absorbed energy per kg.
Both units are defined exactly, so the factor is exact. Rad definition: rad; Gray definition: gray.
Worked examples
- 100 rad is 1 Gy.
100 rad × 0.01 = 1 Gy - A 500 rad dose is 5 Gy.
500 rad × 0.01 = 5 Gy
Rad to Gray conversion table
| Rads (rad) | Grays (Gy) |
|---|---|
| 0.001 rad | 0.00001 Gy |
| 0.01 rad | 0.0001 Gy |
| 0.1 rad | 0.001 Gy |
| 0.5 rad | 0.005 Gy |
| 1 rad | 0.01 Gy |
| 2 rad | 0.02 Gy |
| 5 rad | 0.05 Gy |
| 10 rad | 0.1 Gy |
| 50 rad | 0.5 Gy |
| 100 rad | 1 Gy |
Where it's used
Absorbed doses in rads from US health physics and radiation-hardness specifications are converted to grays. Divide by 100.
Rad to other absorbed dose units
| Conversion | 1 rad equals |
|---|---|
| rad to gray | 0.01 Gy |
| rad to milligray | 10 mGy |
| rad to microgray | 10000 µGy |
| rad to centigray | 1 cGy |
| rad to kilogray | 0.00001 kGy |
| rad to millirad | 1000 mrad |
Frequently asked questions
Is a rad the same as a rem?
Only for X-rays and gamma rays. The rad measures absorbed energy; the rem weights it for the radiation type, so 1 rad of alpha radiation is 20 rem.
How many grays are in 1 rad?
1 rad = 0.01 Gy.
How do I convert rads to grays?
Multiply the value in rad by 0.01, or divide it by 100. For example, 100 rad × 0.01 = 1 Gy.
Is the rad to Gy conversion exact?
Yes. Both units are defined exactly, and 1 rad is exactly 0.01 Gy.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "rad (absorbed dose)".
- 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 Rads to Grays (rad to Gy). Retrieved October 25, 2026, from https://scientificconverters.com/absorbed-dose/rads-to-grays/
IEEE
Scientific Converters, "Convert Rads to Grays (rad to Gy)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/absorbed-dose/rads-to-grays/