Gray is absorbed dose in joules per kilogram.
Grays to Micrograys Converter — Gy to uGy
Convert Gray (Gy) to Microgray (uGy) using the exact conversion factor (1 gray = 1,000,000 microgray). See the formula, worked examples, conversion table, history, and common uses.
Grays to Micrograys 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.
Microgray is 0.000001 gray units.
Result = input x 1 / 1e-6.
Absorbed Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Grays to Micrograys
Gray and Microgray 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
micrograys = grays × 1000000
This factor comes from each unit's defined relationship to the category's base unit: 1 gray equals 1 base unit, and 1 microgray equals 0.000001 base units, so dividing one by the other gives the direct gray-to-microgray factor of 1000000.
Simple example
1 Gy × 1000000 = 1,000,000 uGy
1 gray = 1,000,000 micrograys.
Real-world example
10 Gy × 1000000 = 10,000,000 uGy
10 grays = 10,000,000 micrograys.
Conversion table
| Gray (Gy) | Microgray (uGy) |
|---|---|
| 0.001 Gy | 1,000 uGy |
| 0.01 Gy | 10,000 uGy |
| 0.1 Gy | 100,000 uGy |
| 1 Gy | 1,000,000 uGy |
| 10 Gy | 10,000,000 uGy |
| 100 Gy | 100,000,000 uGy |
Reverse conversion: Microgray to Gray
1 uGy × 0.000001 = 0.000001 Gy
1 microgray = 0.000001 grays.
grays = micrograys × 0.000001
For a page dedicated to this direction, see Microgray 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 Microgray (uGy)
Microgray is 0.000001 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 micrograys are in 1 gray?
1 gray equals 1,000,000 micrograys, using the exact defined conversion factor rather than an estimate.
How do I convert gray to microgray?
Multiply the gray value by 1000000. The converter above does this instantly to whatever precision you set.
How do I convert microgray back to gray?
Use the reverse factor: 1 microgray equals 0.000001 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 microgray?
Microgray (uGy) is a unit of radiation.
Is the gray to microgray conversion exact?
Yes. Both gray and microgray are defined by fixed standards rather than physical artifacts, so the factor of 1000000 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