Convert Rads to Grays
Convert Rads (rad) to Grays (Gy) instantly and accurately.
Conversion Formula
Gy = rad × 0.01
About Rads
The rad (rad) equals exactly 0.01 Gy = 100 erg/g. The pre-SI unit of absorbed dose, defined by the ICRU in 1953, still widely used in the US in radiation therapy (cGy = rad numerically), radiation biology, and NRC regulations. Whole-body 50% lethal dose (LD50) for humans ~350-450 rad. 1 rad = 0.01 Gy = 1 cGy.
About Grays
The gray (Gy) is the SI coherent unit of absorbed radiation dose, defined as 1 joule of energy deposited per kilogram of matter. Named after Harold Gray (British radiobiologist, 1905-1965). Used globally in radiotherapy: curative tumour doses 40-80 Gy fractionated; total body irradiation before bone marrow transplant 12-14 Gy. 1 Gy = 1 J/kg = 100 rad.
Quick Reference Table
| Rads (rad) | Grays (Gy) |
|---|---|
| 1 rad | 0.01 Gy |
| 2 rad | 0.02 Gy |
| 5 rad | 0.05 Gy |
| 10 rad | 0.1 Gy |
| 25 rad | 0.25 Gy |
| 50 rad | 0.5 Gy |
| 100 rad | 1 Gy |