Radiation & Dose Conversion Calculator
Convert between the most common physical radiation units: absorbed dose (Gy, rad), equivalent/effective dose (Sv, rem), exposure (C/kg, roentgen) and activity (Bq, Ci). Physics-only, non-medical use.
Important: this tool is for physical unit conversions only. It must not be used to prescribe medical treatments, assess patient doses or define regulatory dose limits.
Enter a value in any field in the selected group; all other units update instantly.
Absorbed dose
SI unit of absorbed dose.
How radiation & dose units relate to each other
Radiation physics uses several distinct quantities that are often confused in practice:
- Absorbed dose – how much energy from ionising radiation is deposited per kilogram of material (unit: gray, Gy).
- Equivalent / effective dose – absorbed dose weighted by radiation type and tissue sensitivity (unit: sievert, Sv).
- Exposure – ionisation produced in air by X-rays or gamma rays (units: coulomb per kilogram, C/kg, or roentgen, R).
- Activity – rate of nuclear decays in a source (units: becquerel, Bq, or curie, Ci).
Key conversion relationships
Absorbed dose
\(1~\text{Gy} = 1000~\text{mGy} = 10^6~\mu\text{Gy} = 100~\text{rad}\)
Equivalent / effective dose
\(1~\text{Sv} = 1000~\text{mSv} = 10^6~\mu\text{Sv} = 100~\text{rem} = 10^5~\text{mrem}\)
Exposure
\(1~\text{R} \approx 2.58\times10^{-4}~\text{C/kg}\)
Activity
\(1~\text{Ci} = 3.7\times10^{10}~\text{Bq}\)
\(1~\text{mCi} = 3.7\times10^{7}~\text{Bq}, \quad 1~\mu\text{Ci} = 3.7\times10^{4}~\text{Bq}\)
Worked example
Suppose you have an absorbed dose of \(0.02~\text{Gy}\) and want to express it in rad:
- Use the relationship \(1~\text{Gy} = 100~\text{rad}\).
- Multiply: \(0.02~\text{Gy} \times 100 = 2~\text{rad}\).
- Entering
0.02in the Gy field of the calculator automatically returns 2 rad.
Engineering vs. biological meaning
In engineering applications, it is common to work with absorbed dose (Gy, rad) and activity (Bq, Ci) when specifying sources, shielding or test conditions. In radiation protection, the equivalent or effective dose in sievert (Sv) or rem gives a better indication of the potential biological effect for a given exposure scenario.
Always refer to local regulations, safety standards and professional guidance when interpreting radiation quantities in a real project.
FAQ: radiation & dose conversions
Is gray (Gy) always equal to sievert (Sv)?
No. In general, 1 Gy does not correspond to 1 Sv. For some reference situations (such as whole body exposure to photons), numerical values of Gy and Sv can coincide, but in many real cases radiation type and tissue weighting factors make the Sv value differ from the absorbed dose in Gy.
Why do old documents still use rad and rem?
Rad and rem are legacy units widely used before the SI system became standard. Many technical reports, nuclear industry documents and regulatory limits still quote values in rem or mrem. This converter helps bridge between modern SI units and those traditional units without manual calculations.
How precise are the conversions in this tool?
The factors used here (for example, 1 R = 2.58×10−4 C/kg and 1 Ci = 3.7×1010 Bq) follow widely accepted definitions. Results are rounded to a practical number of decimal places, which is usually more than adequate for engineering and educational use.
Can I use this calculator to check regulatory dose limits?
You can use it to convert numerical values between unit systems, but it does not validate whether a given dose is below or above any regulatory limit. Always consult the relevant regulations and, when necessary, a qualified radiation protection expert.
Is patient-specific information considered by this calculator?
No. The calculator does not take into account patient age, tissue type, organ mass, radiation weighting factors or any clinical protocol. It must not be used to design or optimise medical exposures.
Formula (LaTeX) + variables + units
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Absorbed dose \(1~\text{Gy} = 1000~\text{mGy} = 10^6~\mu\text{Gy} = 100~\text{rad}\) Equivalent / effective dose \(1~\text{Sv} = 1000~\text{mSv} = 10^6~\mu\text{Sv} = 100~\text{rem} = 10^5~\text{mrem}\) Exposure \(1~\text{R} \approx 2.58\times10^{-4}~\text{C/kg}\) Activity \(1~\text{Ci} = 3.7\times10^{10}~\text{Bq}\) \(1~\text{mCi} = 3.7\times10^{7}~\text{Bq}, \quad 1~\mu\text{Ci} = 3.7\times10^{4}~\text{Bq}\)
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.