Radiation & Dose Conversion Calculator

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

Worked example

Suppose you have an absorbed dose of 0.02 Gy and want to express it in rad:

1. Use the relationship 1 Gy = 100 rad.
2. Multiply: 0.02 Gy × 100 = 2 rad.
3. Entering 0.02 in 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.