Quick reference table
Common radiation exposure conversions
| From | To |
|---|---|
| 1 R | 0.000258 C/kg |
| 1 C/kg | 3,875.968992 R |
| 1 mR | 0.258 µC/kg |
| 1 R | 1 mR |
How to convert radiation exposure
Exposure measures the ionization produced in air by X-rays or gamma rays. The SI unit is coulombs per kilogram, and the roentgen (R) is the older unit.
Every radiation exposure unit is a fixed multiple of one base unit, the C/kg. To convert a value, multiply it by the size of the starting unit and divide by the size of the target unit. For example, to convert R to C/kg, multiply by 0.000258. To go the other way, divide by 0.000258.
The converter above does this for you and shows the exact formula under the result.
Worked examples
Roentgens to Coulombs per kilogram
| Roentgens (R) | Coulombs per kilogram (C/kg) |
|---|---|
| 1 R | 0.000258 C/kg |
| 2 R | 0.000516 C/kg |
| 5 R | 0.001290 C/kg |
| 10 R | 0.002580 C/kg |
| 25 R | 0.006450 C/kg |
| 50 R | 0.012900 C/kg |
| 100 R | 0.025800 C/kg |
| 1,000 R | 0.258000 C/kg |
Coulombs per kilogram to Roentgens
| Coulombs per kilogram (C/kg) | Roentgens (R) |
|---|---|
| 1 C/kg | 3,875.968992 R |
| 2 C/kg | 7,751.937984 R |
| 5 C/kg | 19,379.84496 R |
| 10 C/kg | 38,759.68992 R |
| 25 C/kg | 96,899.22481 R |
| 50 C/kg | 193,798.4496 R |
| 100 C/kg | 387,596.8992 R |
| 1,000 C/kg | 3,875,968.992 R |
Radiation exposure units explained
| Unit | Symbol | Equals |
|---|---|---|
| Coulombs per kilogram | C/kg | 1 C/kg = 1 C/kg |
| Millicoulombs per kilogram | mC/kg | 1 mC/kg = 0.001 C/kg |
| Microcoulombs per kilogram | µC/kg | 1 µC/kg = 0.000001 C/kg |
| Roentgens | R | 1 R = 0.000258 C/kg |
| Milliroentgens | mR | 1 mR = 2.58 × 10⁻⁷ C/kg |
| Microroentgens | µR | 1 µR = 2.58 × 10⁻¹⁰ C/kg |
Popular conversions: roentgen to c/kg.
Frequently asked questions
How many C/kg is 1 roentgen?
One roentgen is 2.58 × 10⁻⁴ coulombs per kilogram.
How do I convert R to C/kg?
Multiply the value in R by 0.000258 to get C/kg. For example, 10 R = 0.002580 C/kg.
How many C/kg is 1 R?
1 R = 0.000258 C/kg, and 1 C/kg = 3,875.968992 R.
Does this radiation exposure converter work offline?
Yes. After the page has loaded once, all calculations run in your browser, so it keeps working without an internet connection.