Radiation Exposure / R → mR
Convert Roentgens to Milliroentgens
Convert photon exposure in air using charge per mass. Convert Roentgens (R) to Milliroentgens (mR). Find the formula, worked examples, unit definitions, and practical guidance below.
Reverse: Milliroentgens to Roentgens →
How to convert roentgens to milliroentgens
Exposure in C/kg describes ionization in air. It is not absorbed dose in tissue or equivalent dose in sieverts. Those relationships require radiation and material information.
Use x for the value in R, b for the intermediate value in C/kg, and y for the result in mR.
mR = R × 0.000258 ÷ 2.58e-7
Worked examples
10 R ≈ 10000 mR
Step 1: (10 × 0.000258) ≈ 0.00258 C/kg.
Step 2: 0.00258 ÷ 2.58e-7 ≈ 10000 mR.20 R ≈ 20000 mR
Step 1: (20 × 0.000258) ≈ 0.00516 C/kg.
Step 2: 0.00516 ÷ 2.58e-7 ≈ 20000 mR.
Results are rounded to 12 significant digits. Converting units does not increase the precision of the original measurement. Very large or small values outside JavaScript’s finite numeric range are rejected.
About Roentgens
Roentgens (R) measures radiation exposure under the conventions above. The base value in C/kg is (x × 0.000258), where x is the numerical value in R. Factors shown here are rounded for display; calculations use the stored factor.
About Milliroentgens
Milliroentgens (mR) measures radiation exposure under the conventions above. The base value in C/kg is (x × 2.58e-7), where x is the numerical value in mR. Factors shown here are rounded for display; calculations use the stored factor.
Definitions and sources
Carry the same physical assumptions into subsequent physics calculations.
Roentgens to milliroentgens reference table
| Roentgens (R) | Milliroentgens (mR) |
|---|---|
| 1 | 1000 |
| 5 | 5000 |
| 10 | 10000 |
| 25 | 25000 |
| 50 | 50000 |
| 100 | 100000 |
| 1000 | 1000000 |
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