Radiation Exposure Converter — Roentgen & C/kg Converter
Convert radiation exposure between different units including coulomb/kilogram, roentgen, milliroentgen, microroentgen, parker, and more. Essential for radiation protection, dosimetry, and health physics. See also our Radiation Converter and Energy Converter.
Value:
How to Convert Radiation Exposure
- Enter the radiation exposure value in the input field above.
- Select the unit you are converting from in the "From" dropdown menu.
- Select the unit you want to convert to in the "To" dropdown menu.
- The result will automatically appear in the result field.
- Use the copy button to copy the result to your clipboard.
- Click any conversion in the list below to quickly select those units.
Radiation Exposure Formula
Radiation Exposure Definition:
X = dQ/dm
Where:
X = Exposure (C/kg)
dQ = Total charge of ions produced (C)
dm = Mass of air (kg)
Unit Relationships:
1 C/kg = 3876 R (roentgen)
1 R = 2.58 × 10⁻⁴ C/kg
1 mR = 2.58 × 10⁻⁷ C/kg
1 μR = 2.58 × 10⁻¹⁰ C/kg
1 C/g = 1000 C/kg
Conversion:
1 roentgen = 2.58 × 10⁻⁴ C/kg
1 parker (rep) ≈ 1 roentgen (for soft tissue)
1 tissue roentgen ≈ 1 roentgenExample Conversion
Problem: Convert 500 mR to C/kg.
Given: X = 500 mR
Solution:
• 500 mR × 2.58 × 10⁻⁷ C/kg per mR = 1.29 × 10⁻⁴ C/kg
Answer: 500 mR = 1.29 × 10⁻⁴ C/kg = 0.5 R
Technical Details
Radiation exposure measures the ionization produced in air by X-rays or gamma rays. The SI unit is coulomb per kilogram (C/kg), while the older unit roentgen (R) is still widely used in practice. One roentgen equals 2.58 × 10⁻⁴ C/kg, representing the amount of radiation that produces 2.58 × 10⁻⁴ coulombs of charge per kilogram of dry air.
The roentgen was one of the first radiation units defined (1928) and remains in common use for measuring X-ray output and environmental radiation levels. The parker (rep, roentgen equivalent physical) was an early attempt to relate exposure to absorbed dose in tissue. Survey meters and area monitors often display readings in mR/hr or μR/hr for radiation protection purposes.
Radiation Exposure Reference Table
| Source | Typical Exposure | Context |
|---|---|---|
| Chest X-ray | 10-20 mR | Diagnostic imaging |
| Dental X-ray | 1-5 mR | Dental imaging |
| Background radiation | 100-300 mR/year | Natural sources |
| CT scan | 1000-5000 mR | Diagnostic imaging |
| Fluoroscopy | 2-5 R/min | Real-time imaging |
| Nuclear plant limit | 100 mR/year | Public exposure limit |
| Occupational limit | 5 R/year | Radiation worker |
| Emergency response | 25 R | Life-saving actions |
Frequently Asked Questions
What is the difference between exposure and absorbed dose?
Exposure (measured in roentgen or C/kg) quantifies ionization in air only, while absorbed dose (measured in gray or rad) measures energy deposited in any material. Exposure is specific to photon radiation in air, whereas absorbed dose applies to any radiation type in any medium.
How do you convert roentgen to C/kg?
Multiply the value in roentgen by 2.58 × 10⁻⁴ to get C/kg. For example, 1 R = 2.58 × 10⁻⁴ C/kg. Conversely, divide C/kg by 2.58 × 10⁻⁴ (or multiply by 3876) to get roentgen.
Why is the roentgen still used if C/kg is the SI unit?
The roentgen remains in widespread use because many existing instruments are calibrated in R or mR, regulatory limits reference it, and it provides convenient numbers for typical radiation levels. The transition to SI units is gradual in radiation protection practice.
What is a parker (rep)?
The parker or rep (roentgen equivalent physical) is an obsolete unit that attempted to express absorbed dose in tissue equivalent to 1 roentgen of exposure. It equals approximately 0.93 rad or 9.3 mGy. It has been superseded by the gray and rad.
What radiation levels are considered safe?
Background radiation is typically 100-300 mR/year. Occupational limits are 5 R/year (US) or about 2 R/year (ICRP). Public limits are 100 mR/year above background. Survey meter readings above 2 mR/hr in unrestricted areas typically require investigation.
Objective of Measurement:
Measurement is the most important aspect of our life. We use measurement in science, engineering, business trading, personal life, education, and more other fields. As technology is growing day by day so we need a highly accurate and easy convenient global measuring system in each and every field. It is essential to use standard measurement in every field that everyone to be sure that they not get cheated.
History of Measurement:
In history for measurement people used the human body as a tool. For measuring length used forearm, hand, foot & finger as a unit. The foot, finger is a subdivided shorter unit of a length. This type of measurement is not accurate cause different in size of the arm & finger for different people & some of the countries still using it. In history, there were lots of measuring systems developed but mostly used imperial, the metric system of measurement. We use these systems for measure distances, volume, weight, speed, area etc. Due to this a major problem everyone is facing while doing trading between the countries. A huge improvement in civilization, It necessary to improve measuring standards. Nowadays International Standard (SI) units are used as a global measurement system.
Radiation Exposure Conversion - Unit Converter:
Our radiation exposure conversion converter convert coulomb/kilogram [C/kg], millicoulomb/kilogram [mC/kg], microcoulomb/kilogram [μC/kg], roentgen [R], milliroentgen [mR], microroentgen [μR], tissue roentgen [TR], parker [rep], coulomb/gram [C/g] vice versa with metric conversion.
Radiation exposure conversions & its abbreviations
| Unit | Abbreviation | Unit | Abbreviation |
|---|---|---|---|
| coulomb/kilogram | C/kg | millicoulomb/kilogram | mC/kg |
| microcoulomb/kilogram | μC/kg | roentgen | R |
| milliroentgen | mR | microroentgen | μR |
| tissue roentgen | TR | parker | rep |
| coulomb/gram | C/g |
Complete list of Radiation exposure conversion units and its conversion.
1 coulomb/kilogram [C/kg] = 3876 roentgen [R]
1 roentgen [R] = 2.58e-4 coulomb/kilogram [C/kg]
1 coulomb/kilogram [C/kg] = 1000 millicoulomb/kilogram [mC/kg]
1 roentgen [R] = 1000 milliroentgen [mR]
1 milliroentgen [mR] = 0.001 roentgen [R]
1 roentgen [R] = 1000000 microroentgen [μR]
1 coulomb/gram [C/g] = 1000 coulomb/kilogram [C/kg]
1 parker [rep] = 1 roentgen [R] (approx.)