Gray measures energy absorbed per kilogram; sievert adjusts for how damaging each type of radiation is. Alpha particles deposit their energy densely and are about 20 times more harmful per gray than X-rays.
How to use the Radiation Dose Converter
- Absorbed dose
- Radiation type
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the absorbed dose and choose the radiation type.
Tips
- Keep a record of your imaging and its doses.
- Ask whether an ultrasound or MRI could answer the question without radiation.
- Tell staff if you might be pregnant.
- Background radiation varies by altitude and region.
Common mistakes to avoid
- Comparing mSv (effective dose) with mGy (absorbed dose).
- Assuming every scan of the same type gives the same dose.
- Ignoring cumulative dose from repeated scans.
Inputs explained
| Field | What to enter |
|---|---|
| Absorbed dose | Units: Gy, mGy, rad |
| Radiation type | Choose one: X-rays, gamma rays, electrons (wR 1), Protons (wR 2), Neutrons, typical (wR 10), Alpha particles (wR 20) |
What each result means
- Equivalent dose = [Absorbed dose]×[Radiation type]
- Absorbed dose in rad = [Absorbed dose]×100
Example values
How the main result changes when Absorbed dose changes and everything else stays at the example values above:
| Absorbed dose (Gy) | Equivalent dose (mSv) |
|---|---|
| 0.005 | 5 |
| 0.0075 | 7.5 |
| 0.01 | 10 |
| 0.0125 | 12.5 |
| 0.015 | 15 |
| 0.02 | 20 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Equivalent dose (Sv) = absorbed dose (Gy) × radiation weighting factor (wR)
1 Gy = 100 rad · 1 Sv = 100 rem
wR: photons and electrons 1, protons 2, alpha particles 20, neutrons 2.5–20
Worked example
Inputs — Absorbed dose: 0.01 Gy; Radiation type: X-rays, gamma rays, electrons (wR 1).
Results — Equivalent dose = 10 mSv; Absorbed dose in rad = 1.
Key terms
- wR
- Radiation weighting factor.
Frequently asked questions
What is the difference between gray and sievert?
Gray is absorbed energy; sievert reflects biological harm.
How much radiation causes sickness?
Acute doses above about 1 Gy to the whole body can cause radiation sickness.
What is the annual limit for radiation workers?
20 mSv a year averaged over 5 years (ICRP).