What does this radiation & dose conversion calculator do?

This radiation & dose conversion calculator converts between the most common physical radiation units: absorbed dose (gray, milligray, microgray, rad), equivalent or effective dose (sievert, millisievert, microsievert, rem, millirem), exposure (coulomb per kilogram and roentgen), and activity (becquerel, kilobecquerel, megabecquerel, gigabecquerel, curie, millicurie and microcurie). It is designed for physics and engineering use only and not for medical decision-making.

What is the difference between gray (Gy) and sievert (Sv)?

Gray (Gy) is a physical unit of absorbed dose and measures how much energy from ionising radiation is deposited per kilogram of material. Sievert (Sv) is a weighted unit that also considers the type of radiation and the sensitivity of the irradiated tissue. One gray of alpha radiation does not imply the same biological effect as one gray of X-rays, which is why the sievert is used in radiological protection.

How are rad and rem related to gray and sievert?

Rad and rem are older, non-SI units still used in some industries. For absorbed dose, 1 gray (Gy) corresponds to 100 rad. For equivalent or effective dose, 1 sievert (Sv) corresponds to 100 rem. The calculator automatically converts between these legacy units and their SI counterparts.

Can I use this calculator for medical dose prescriptions or safety limits?

No. This tool is intended only for physical unit conversions and educational or engineering-related estimates. It does not account for patient-specific factors, radiation weighting factors or regulatory dose constraints. For any medical use or safety assessment, consult qualified health physics or medical professionals and follow local regulations.

What level of precision does the converter use?

The tool uses fixed physical relationships such as 1 Gy = 100 rad, 1 Sv = 100 rem, 1 Ci = 3.7×10^10 Bq and 1 R = 2.58×10^-4 C/kg. Results are rounded to a practical number of decimal places for readability, but they should still be considered approximations suitable for engineering calculations and not for critical safety limits.

Radiation & Dose Conversion Calculator – Convert gray, sievert, rad, rem & more

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 0.02 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.