Roentgen (R)
Older unit of exposure to X-rays and gamma rays in air: exactly 2.58 × 10⁻⁴ C/kg.
What is a roentgen?
- Symbol
- R
- Quantity
- Radiation Exposure
- Unit system
- other
- Definition
- Older unit of exposure to X-rays and gamma rays in air: exactly 2.58 × 10⁻⁴ C/kg.
- Exact
- Yes, the value is exact by definition
- Source
- NIST Special Publication 811 (2008), Appendix B.8
Common applications
Still found on older survey meters and in US radiation safety and civil defense literature.
Roentgen in other radiation exposure units
- 1 R = 0.000258 C/kgRoentgen to Coulomb per kilogram converter
- 1 R = 0.258 mC/kgMillicoulomb per kilogram
- 1 R = 1000 mRMilliroentgen
- 1 R = 1000000 µRMicroroentgen
Roentgen quick reference
| Roentgen | Coulomb per kilogram | Millicoulomb per kilogram | Milliroentgen |
|---|---|---|---|
| 1 R | = 0.000258 C/kg | = 0.258 mC/kg | = 1000 mR |
| 10 R | = 0.00258 C/kg | = 2.58 mC/kg | = 10000 mR |
| 100 R | = 0.0258 C/kg | = 25.8 mC/kg | = 100000 mR |
| 1000 R | = 0.258 C/kg | = 258 mC/kg | = 1000000 mR |
Where the roentgen fits
The next smaller radiation exposure unit is the milliroentgen (mR). 1 R = 1000 mR, and 1 mR = 0.001 R.
The next larger radiation exposure unit is the millicoulomb per kilogram (mC/kg). 1 R = 0.258 mC/kg, and 1 mC/kg ≈ 3.875968992 R.
Frequently asked questions
- How many coulombs per kilogram are in one roentgen?
- One roentgen = 0.000258 C/kg (coulombs per kilogram).
- How many millicoulombs per kilogram are in one roentgen?
- One roentgen = 0.258 mC/kg (millicoulombs per kilogram).
- How many milliroentgens are in one roentgen?
- One roentgen = 1000 mR (milliroentgens).