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Radiation dose equivalent — how much biological harm a radiation exposure could cause — is measured in Sievert in the SI system, but rem remains common in the US and in older references. This calculator converts between Sievert, millisievert, microsievert, and rem, which are all directly proportional to each other.
This tool covers dose equivalent units only. Absorbed-dose units like Gray and rad use a different radiation-weighting basis and aren't included here, to avoid implying a false direct equivalence between the two systems.
How it works
Enter a value, choose the unit you're converting from and to, and the calculator applies the standard conversion factor between Sievert, millisievert, microsievert, and rem.
- Enter value.
- Enter from.
- Enter to.
- Click Calculate to see your results.
Examples
Annual background radiation exposure
A typical annual background exposure of about 3 millisievert converts to 0.3 rem, useful when comparing against US-based reference values.
A medical imaging dose
A CT scan dose reported in millisievert is converted to microsievert for finer-grained comparison against other diagnostic procedures.
Who should use it
- Comparing radiation exposure figures reported in Sievert-based vs. rem-based sources.
- Converting medical imaging dose figures between millisievert and microsievert.
Industry applications
- Radiology and nuclear medicine
- Radiation safety and health physics
Advantages
- Covers both SI (Sievert) and traditional (rem) dose equivalent systems.
- Shows the exact conversion factor used, not just the final answer.
- No account, subscription or watermark.
Limitations
- Covers dose equivalent only, not absorbed dose (Gray/rad) — those use a different, non-directly-proportional basis.
Common mistakes to avoid
- Assuming Gray/rad and Sievert/rem are interchangeable, when they measure different (though related) quantities.
- Confusing dose equivalent with radioactivity (decay rate), which uses entirely different units (Becquerel/Curie).
Best practices
- Confirm which specific quantity (dose equivalent vs. absorbed dose) a source is actually reporting before converting.
- Use microsievert for very small doses like typical medical imaging, to keep numbers readable.
Tips
- Remember that 1 Sievert equals exactly 100 rem for quick mental conversion.
- Don't confuse this with the Radioactivity Converter, which measures decay rate rather than biological dose.