Free Radiation Converter

Radiation Converter is a free online tool that handles all common radiation unit conversions, including Sv to Gy, Rad to Rem, and many more. Whether you need a Sievert converter, a Gray to Rad converter, or a comprehensive Radiation Unit Converter, this utility covers absorbed dose, equivalent dose, and effective dose units — from gray (Gy) and rad to sievert (Sv), rem, and even the informal banana equivalent dose (BED). The straightforward interface lets you switch instantly between unit systems, making it ideal for professionals in dosimetry, radiology, and radiation protection.

Absorbed Dose

Absorbed dose quantifies the energy deposited by ionizing radiation per unit mass of the irradiated material. Its SI unit is the gray (1 Gy = 1 J/kg). Additional units include:

• Microgray (µGy)
• Milligray (mGy)
• Centigray (cGy)
• Rad (CGS unit, where 1 rad = 0.01 Gy)

The converter enables seamless transitions among these values. For example, entering a measurement in mGy instantly shows the equivalent in rad and other selectable options. This quantity is fundamental to dosimetry, radiology, and radiation protection.

Equivalent Dose

While absorbed dose reflects pure physical energy, equivalent dose adjusts for the biological effectiveness of different radiation types. It is calculated as:

$$H_T = \sum W_R \cdot D_{T,R}$$

where $H_T$ is the equivalent dose in sieverts (Sv) for tissue $T$, $D_{T,R}$ is the absorbed dose in grays (Gy) from radiation type $R$, and $W_R$ is the dimensionless radiation weighting factor. The International Commission on Radiological Protection (ICRP Publication 103, 2007) defines the following weighting factors:

Radiation type	$W_R$
X‑rays, gamma rays, beta particles, muons	1
Neutrons (<1 MeV)	$2.5 + 18.2 e^{-(\ln E)^2/6}$
Neutrons (1–50 MeV)	$5.0 + 17.0 e^{-[\ln(2E)]^2/6}$
Neutrons (>50 MeV)	$2.5 + 3.25 e^{-[\ln(0.04E)]^2/6}$
Protons, charged pions	2
Alpha particles, nuclear fission products, heavy nuclei	20

E denotes neutron energy in MeV.

The base unit of equivalent dose is the sievert (Sv). The converter can express equivalent dose in microsieverts (µSv), millisieverts (mSv), millirems (mrem), rems, or banana equivalent doses (BED) — the latter being a colloquial unit used to make small radiation exposures relatable.

Effective Dose

Effective dose extends the concept by summing weighted equivalent doses across all tissues and organs:

$$E = \sum W_T \cdot H_T$$

where $E$ is the effective dose to the whole body (Sv), $W_T$ is the tissue weighting factor, and $H_T$ is the equivalent dose for tissue $T$. Tissues with higher radiosensitivity receive larger weighting factors. The ICRP‑103 tissue weighting factors are:

Organ	$W_T$
Colon	0.19
Lung	0.16
Red bone marrow	0.13
Stomach	0.12
Breasts	0.12
Gonads	0.08
Bladder	0.04
Liver	0.04
Esophagus	0.04
Thyroid	0.04
Skin	0.01
Bone surface	0.01
Salivary glands	0.01
Brain	0.01
Remainder of the body	0.12
Total	1.00

Because effective dose uses the same base units as equivalent dose, the converter applies the same set of unit options (Sv, mSv, µSv, rem, mrem, BED) to both measurements.

How to Convert Units

Using the calculator follows a simple workflow:

1. Select the dose type — absorbed, equivalent, or effective.
2. Type a numeric value into the corresponding field (for instance, 0.1 mSv, the typical effective dose from a chest X‑ray).
3. The tool immediately displays the converted amounts in two other units (e.g., 100 µSv and 0.01 rem). You can also change the output units from the dropdown menus to perform specific conversions such as Sv to Gy or Rad to Rem.

The radiation converter streamlines switching between conventional and SI units, delivering quick, accurate results for any radiation‑related calculation.