Convert Grays to Rads (Gy to rad)
1 gray (Gy) = 100 rads (rad). 1 rad = 0.01 Gy. Example: 2 Gy = 2 × 100 = 200 rad.
Also searched as Gy to rad, grays to rads, gray to rad conversion and cGy to rad.
1 Gy = 100 rad
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk gray to rad converter to paste a column from Excel.
How to Convert Gray to Rad
- 1 Gy = 100 rad
- 1 rad = 0.01 Gy
- Example: convert 2 Gy to rad: 2 Gy = 2 × 100 rad = 200 rad
Formula
rad = Gy × 100
Derivation from SI units:
- 1 Gy = 1 J of absorbed energy per kg.
- 1 rad = 100 erg/g = 0.01 Gy.
Both units are defined exactly, so the factor is exact. Gray definition: gray; Rad definition: rad.
Worked examples
- A 2 Gy radiotherapy fraction is 200 rad.
2 Gy × 100 = 200 rad - 1 Gy is 100 rad.
1 Gy × 100 = 100 rad
Gray to Rad conversion table
| Grays (Gy) | Rads (rad) |
|---|---|
| 0.001 Gy | 0.1 rad |
| 0.01 Gy | 1 rad |
| 0.1 Gy | 10 rad |
| 0.5 Gy | 50 rad |
| 1 Gy | 100 rad |
| 2 Gy | 200 rad |
| 5 Gy | 500 rad |
| 10 Gy | 1000 rad |
| 50 Gy | 5000 rad |
| 100 Gy | 10000 rad |
Where it's used
Absorbed doses in grays from radiotherapy plans and dosimetry reports are converted to rads for US documents and older references. Multiply by 100.
Gray to other absorbed dose units
| Conversion | 1 Gy equals |
|---|---|
| gray to rad | 100 rad |
| gray to milligray | 1000 mGy |
| 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 rads are in a gray?
Exactly 100: 1 Gy = 100 rad, so 1 cGy equals 1 rad.
How many rads are in 1 gray?
1 Gy = 100 rad.
How do I convert grays to rads?
Multiply the value in Gy by 100. For example, 2 Gy × 100 = 200 rad.
Is the Gy to rad conversion exact?
Yes. Both units are defined exactly, and 1 Gy is exactly 100 rad.
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).
- 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)".
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 Rads (Gy to rad). Retrieved October 25, 2026, from https://scientificconverters.com/absorbed-dose/grays-to-rads/
IEEE
Scientific Converters, "Convert Grays to Rads (Gy to rad)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/absorbed-dose/grays-to-rads/