Radiation Converter Calculator

Understanding Absorbed Dose Units

Absorbed dose measures the energy that ionizing radiation deposits per unit mass of material or tissue. The SI standard is the gray (Gy), defined as one joule of energy absorbed per kilogram. Most clinical applications use milligrays (mGy) or microgray (µGy) for precision.

The older CGS unit, the rad (radiation absorbed dose), equals 0.01 Gy. Many legacy instruments and older literature reference rads, so conversion between rad and gray remains common in healthcare and research environments.

• Gray (Gy): SI unit; 1 Gy = 1 joule per kilogram
• Milligray (mGy): Used for diagnostic and therapeutic doses; 1 mGy = 0.001 Gy
• Rad: CGS unit; 1 rad = 0.01 Gy

Equivalent Dose and Biological Weighting

Absorbed dose alone doesn't account for how different radiation types damage tissue. The equivalent dose factors in this biological effect using radiation weighting factors. The relationship is captured by multiplying the absorbed dose by the type-specific weighting factor.

For example, alpha particles are far more damaging to living tissue than beta or gamma radiation at the same absorbed dose. The sievert (Sv) is the SI unit for equivalent dose, while the older rem (roentgen equivalent man) equals 0.01 Sv. Medical reports often express doses in millisieverts (mSv) or microsieverts (µSv).

Effective dose extends this further by accounting for how sensitive different organs are to radiation—the colon and lungs are more radiosensitive than the brain or bone, so the same absorbed dose to different organs yields different effective doses.

Radiation Dose Conversion Relationships

The following relationships underpin all conversions in this tool:

• Gy — Gray; SI unit of absorbed dose
• mGy — Milligray; one-thousandth of a gray
• rad — Radiation absorbed dose; CGS unit equal to 0.01 Gy
• Sv — Sievert; SI unit of equivalent and effective dose
• mSv — Millisievert; one-thousandth of a sievert
• rem — Roentgen equivalent man; older unit equal to 0.01 Sv

Common Pitfalls and Practical Considerations

Avoid these mistakes when converting or interpreting radiation doses.

1. Don't confuse absorbed and effective dose — A dose listed in gray is absorbed energy only—it does not account for radiation type or organ sensitivity. Sieverts factor in both. Medical reports use sieverts for this reason. Always check which unit appears on your report before comparing limits or risks.
2. Rem and sievert confusion in older literature — Older textbooks and some industrial safety data still use rem. Remember that 1 rem = 0.01 Sv, so a 50 rem exposure is 0.5 Sv. Mixing these units without conversion can lead to misinterpretation of historical exposure records.
3. BED is informal and context-dependent — Banana equivalent dose (BED) is a rough, non-standard analogy for public communication. It varies by banana source and potassium content, so never use it for regulatory compliance, medical decisions, or formal risk assessment.
4. Dose rate vs. total dose matters — A converter shows instantaneous or total values, but health effects depend on both dose and how quickly it was received. 1 Sv delivered over weeks differs from 1 Sv delivered in seconds; always factor in exposure duration when assessing risk.

Practical Application: Reading a Medical Report

A typical chest X-ray report states an effective dose of 0.1 mSv. Using this converter, you can instantly determine that this equals 100 µSv, 0.0001 Sv, and approximately 0.01 rem. This allows you to compare the dose against regulatory limits (usually expressed in different units by different bodies) and benchmark it against annual background radiation exposure.

If a report uses absorbed dose in mGy, the converter bridges to sieverts by applying the appropriate weighting factors for the radiation type and organs involved. For diagnostic imaging, this typically results in lower sievert values than absorbed gray values because diagnostic X-rays and gamma radiation have lower weighting factors than, say, neutrons or alpha particles.