Gray is absorbed dose in joules per kilogram.
Grays to Centigrays Converter — Gy to cGy
Convert Gray (Gy) to Centigray (cGy) using the exact conversion factor (1 gray = 100 centigray). See the formula, worked examples, conversion table, history, and common uses.
Grays to Centigrays converter
Converter
Radiation Converter
Convert radioactivity, absorbed dose, and equivalent dose units by compatible radiation family.
Context values
Some unit families need one extra value for a physically accurate result.
Centigray is 0.01 gray units.
Result = input x 1 / 0.01.
Absorbed Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Grays to Centigrays
Gray and Centigray both belong to the radiation-measurement family, though radiation quantities fall into genuinely distinct categories: absorbed dose (gray, rad) measures energy deposited in matter, equivalent dose (sievert, rem) weights that for biological harm, and activity (becquerel, curie) measures how often a radioactive source decays — this page only converts between units of the same kind. Gray is most often used for radiation therapy dose prescriptions in medicine.
Formula
centigrays = grays × 100
This factor comes from each unit's defined relationship to the category's base unit: 1 gray equals 1 base unit, and 1 centigray equals 0.01 base units, so dividing one by the other gives the direct gray-to-centigray factor of 100.
Simple example
1 Gy × 100 = 100 cGy
1 gray = 100 centigrays.
Real-world example
10 Gy × 100 = 1,000 cGy
10 grays = 1,000 centigrays.
Conversion table
| Gray (Gy) | Centigray (cGy) |
|---|---|
| 0.001 Gy | 0.1 cGy |
| 0.01 Gy | 1 cGy |
| 0.1 Gy | 10 cGy |
| 1 Gy | 100 cGy |
| 10 Gy | 1,000 cGy |
| 100 Gy | 10,000 cGy |
Reverse conversion: Centigray to Gray
100 cGy × 0.01 = 1 Gy
100 centigrays = 1 gray.
grays = centigrays × 0.01
For a page dedicated to this direction, see Centigray to Gray.
Understanding the Gray
Gray (Gy) measures absorbed radiation dose. The SI derived unit of absorbed radiation dose, equal to one joule of radiation energy absorbed per kilogram of matter. It is classified as a SI derived unit.
Where it's used: Universal — SI derived unit used worldwide in medicine and radiation protection
Gray vs. sievert. The gray measures physically absorbed energy; the sievert measures equivalent dose, which weights the gray value for how biologically damaging a given type of radiation is. The same absorbed dose in gray can correspond to different sievert values depending on the radiation type.
Uses of the Gray today
- Radiation therapy dose prescriptions in medicine
- Radiation safety and occupational dose monitoring
- Nuclear and radiological research
History of the Gray
The gray is named after Louis Harold Gray (1905–1965), a British physicist who pioneered the physics of radiation dosimetry and its biological effects, and was adopted by the CGPM as an SI derived unit in 1975.
Historical origin. Gray was not the invention of a single named person; it developed through the process described above.
Understanding the Centigray (cGy)
Centigray is 0.01 gray units.
Gray — sources
- BIPM SI Brochure, 9th edition — Official definition of the gray as an SI derived unit.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many centigrays are in 1 gray?
1 gray equals 100 centigrays, using the exact defined conversion factor rather than an estimate.
How do I convert gray to centigray?
Multiply the gray value by 100. The converter above does this instantly to whatever precision you set.
How do I convert centigray back to gray?
Use the reverse factor: 1 centigray equals 0.01 grays. You can also use the swap control in the converter above to flip the direction instantly.
What is a gray?
Gray (Gy) measures absorbed radiation dose. The SI derived unit of absorbed radiation dose, equal to one joule of radiation energy absorbed per kilogram of matter. It is classified as a SI derived unit.
What is a centigray?
Centigray (cGy) is a unit of radiation.
Is the gray to centigray conversion exact?
Yes. Both gray and centigray are defined by fixed standards rather than physical artifacts, so the factor of 100 used above is exact to as many digits as you choose to display.
What is the difference between gray vs. sievert?
The gray measures physically absorbed energy; the sievert measures equivalent dose, which weights the gray value for how biologically damaging a given type of radiation is. The same absorbed dose in gray can correspond to different sievert values depending on the radiation type.
Where is the gray still used today?
Universal — SI derived unit used worldwide in medicine and radiation protection