Radiation Dose Unit Converter

Instantly convert between Sv, Gy, rem, rad, and more

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Quick Guide

Sievert (Sv)

Standard unit for equivalent dose (biological risk).

1 Sv = 1000 mSv = 100 rem

Gray (Gy)

Unit for absorbed dose (energy deposited).

1 Gy = 100 rad

rem

Older US unit for equivalent dose.

1 rem = 10 mSv = 0.01 Sv
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For X-rays and Gamma rays, 1 Gy ≈ 1 Sv (Weighting factor = 1).

Radiation Units Explained

Absorbed vs Equivalent Dose

Absorbed Dose (Gy): Measures the physical energy deposited in matter by radiation. It tells you "how much" energy hit the tissue.

Equivalent Dose (Sv): Measures the biological effect. It takes the absorbed dose and multiplies it by a "radiation weighting factor" (Wr) because some types of radiation (like Alpha particles) are more damaging than others (like X-rays).

For diagnostic X-rays, Wr = 1, so 1 Gray is physically equal to 1 Sievert.

SI vs US Units

Most of the world uses the System International (SI) units (Gray and Sievert). The United States still commonly uses the older units (rad and rem).

  • 1 Sv = 100 rem
  • 1 mSv = 100 mrem
  • 1 Gy = 100 rad
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Medical Disclaimer: This tool is provided for educational and informational purposes only. Results are estimates based on typical values and should not be used as a substitute for professional medical advice, diagnosis, or treatment.