Convert Roentgens to Millicoulombs per kilogram
Convert Roentgens (R) to Millicoulombs per kilogram (mC/kg) instantly and accurately.
Conversion Formula
mC/kg = R × 0.258
About Roentgens
The roentgen (R) equals exactly 2.58 × 10⁻⁴ C/kg, the historical unit of X-ray and gamma-ray exposure defined in 1928 (ICRU) and redefined exactly in 1962. Still widely used in the US: field survey instruments read in R/h; NRC and EPA regulations cite R and mR; the Chernobyl accounts famously reported readings in R/h. 1 R = 2.58 × 10⁻⁴ C/kg.
About Millicoulombs per kilogram
The millicoulomb per kilogram (mC/kg) equals 10⁻³ C/kg ≈ 3.88 R. Used in high-dose-rate X-ray beam calibration protocols (IAEA TRS-398, AAPM TG-51) where free-air chambers accumulate mC/kg of charge per irradiation; high-energy medical linac beams deliver calibration exposures measured in mC/kg. 1 mC/kg = 10⁻³ C/kg ≈ 3.88 R.
Quick Reference Table
| Roentgens (R) | Millicoulombs per kilogram (mC/kg) |
|---|---|
| 1 R | 0.258 mC/kg |
| 2 R | 0.516 mC/kg |
| 5 R | 1.29 mC/kg |
| 10 R | 2.58 mC/kg |
| 25 R | 6.45 mC/kg |
| 50 R | 12.9 mC/kg |
| 100 R | 25.8 mC/kg |