Convert radiation exposure units in real time. Easily calculate conversions across 7 units, including C/kg, mC/kg, µC/kg, and Roentgen [R]. Free, fast, and 100% accurate.
Radiation Exposure Converter
Radiation Exposure Converter & Guide
Easily convert between all standard units of radiation exposure (ionization in air), including Coulomb/kilogram [C/kg], Millicoulomb/kilogram [mC/kg], Microcoulomb/kilogram [µC/kg], Roentgen [R], Tissue Roentgen, Parker, and Rep [roentgen equivalent physical].
What is Radiation Exposure?
Radiation Exposure quantifies the amount of electrical charge (ionization) produced by X-rays or gamma rays per unit mass of dry air at standard pressure and temperature.
Key definitions and standards include:
- Coulomb per kilogram [C/kg]: The official International System of Units (SI) unit for radiation exposure. It represents the quantity of X- or gamma radiation that produces 1 Coulomb of electric charge (ions of one sign) in 1 kilogram of air.
- Roentgen [R]: The traditional legacy unit named after Wilhelm Röntgen. Exactly 1 Roentgen = 0.000258 C/kg (or 2.58 × 10-4 C/kg).
- Tissue Roentgen, Parker, and Rep: Legacy non-SI units introduced in early health physics and radiology to extend exposure measurement concepts to biological tissues. For standard exposure conversion, 1 Tissue Roentgen, 1 Parker, and 1 Rep are each equivalent to 0.000258 C/kg.
Supported Radiation-Exposure Units
1. SI Units
- Coulomb/kilogram [C/kg]: The standard SI base unit for radiation exposure.
- Millicoulomb/kilogram [mC/kg]: 1 mC/kg = 0.001 C/kg (1.0E-03 C/kg).
- Microcoulomb/kilogram [µC/kg]: 1 µC/kg = 0.000001 C/kg (1.0E-06 C/kg).
2. Traditional & Legacy Units
- Roentgen [R]: The traditional unit for radiation exposure in air (1 R = 0.000258 C/kg).
- Tissue Roentgen: Historical unit adapted for exposure in soft biological tissue (1 tissue roentgen = 0.000258 C/kg).
- Parker: Historical exposure/dose unit named after Herbert Parker (1 parker = 0.000258 C/kg).
- Rep [roentgen equivalent physical]: Early dose/exposure unit developed before the Gray or Rad (1 rep = 0.000258 C/kg).
Unit Conversion Formulas
Use Coulomb/kilogram [C/kg] as the base unit to convert between any of these radiation exposure units:
1. Converting from Coulomb/kilogram [C/kg]
- To Roentgen [R]: R = C/kg ÷ 0.000258 (or C/kg × 3,875.96899)
- To Tissue Roentgen: tissue roentgen = C/kg ÷ 0.000258
- To Parker: parker = C/kg ÷ 0.000258
- To Rep: rep = C/kg ÷ 0.000258
- To Millicoulomb/kilogram [mC/kg]: mC/kg = C/kg × 1,000
- To Microcoulomb/kilogram [µC/kg]: µC/kg = C/kg × 1,000,000
2. Converting to Coulomb/kilogram [C/kg]
- From Roentgen [R]: C/kg = R × 0.000258
- From Tissue Roentgen: C/kg = tissue roentgen × 0.000258
- From Parker: C/kg = parker × 0.000258
- From Rep: C/kg = rep × 0.000258
- From Millicoulomb/kilogram [mC/kg]: C/kg = mC/kg × 0.001
- From Microcoulomb/kilogram [µC/kg]: C/kg = µC/kg × 0.000001
Radiation Exposure Conversion Table
The table below provides equivalent exposure values relative to 1 unit of each measure:
| Unit Name | Symbol | Equivalent in C/kg | Scientific / Exact Value |
|---|---|---|---|
| Microcoulomb/kilogram | µC/kg | 0.000001 C/kg | 1.0E-06 C/kg |
| Millicoulomb/kilogram | mC/kg | 0.001 C/kg | 1.0E-03 C/kg |
| Roentgen | R | 0.000258 C/kg | 2.58E-04 C/kg |
| Tissue Roentgen | tissue roentgen | 0.000258 C/kg | 2.58E-04 C/kg |
| Parker | parker | 0.000258 C/kg | 2.58E-04 C/kg |
| Rep (roentgen equivalent physical) | rep | 0.000258 C/kg | 2.58E-04 C/kg |
| Coulomb/kilogram | C/kg | 1 C/kg | 1.0E+00 C/kg |
Step-by-Step Conversion Examples
Example 1: Convert 500 Roentgen [R] to Coulomb/kilogram [C/kg]
Formula: C/kg = R × 0.000258
Calculation: 500 × 0.000258 = 0.129 C/kg
Result: 500 R is equal to 0.129 C/kg (or 129 mC/kg).
Example 2: Convert 0.005 Coulomb/kilogram [C/kg] to Roentgen [R]
Formula: R = C/kg ÷ 0.000258
Calculation: 0.005 ÷ 0.000258 ≈ 19.3798 R
Result: 0.005 C/kg is equal to approximately 19.38 R.
Frequently Asked Questions (FAQ)
What is the difference between Radiation Exposure (C/kg) and Absorbed Dose (Gray)?
Exposure (C/kg or Roentgen) measures the ionization created specifically in dry air by X-rays or gamma radiation. Absorbed Dose (Gray or Rad) measures the physical energy absorbed by any material or tissue exposed to any type of ionizing radiation.
What does “rep” stand for?
Rep stands for “roentgen equivalent physical.” It was an early radiological unit introduced to measure the absorbed dose in tissue that produces the same energy dissipation as 1 roentgen of X-rays in air (approximately 93 ergs per gram of tissue).
Why is 1 Roentgen equal to 0.000258 C/kg?
The original electrostatic definition of 1 Roentgen was 1 electrostatic unit of charge (esu) per 0.001293 grams of dry air. When converted into standard SI physical units, 1 esu/cm³ of air translates directly to 2.58 × 10-4 Coulombs per kilogram (0.000258 C/kg).
