Radiation Units and Conversion Factors

• International System of Units (SI) Unit and Common Unit Terminology
• Conversion Equivalence
• Prefixes Often Used with SI Units
• Dose Unit Conversion Tool
• Radioactivity Unit Conversion Tool
• Exposure Unit Conversion Tool
• Conversion Factors
• References

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International System of Units (SI) Unit and Common Unit Terminology

	SI Units*	Common Units
Radioactivity	becquerel (Bq)	curie (Ci)
Absorbed Dose	gray (Gy)	rad
Dose Equivalent	sievert (Sv)	rem
Exposure	coulomb/kilogram (C/kg)	roentgen (R)

* SI Units: International System of Units

Note: In the table above the common units and SI units in each row are not equivalent in value, i.e., 1 curie does not equal 1 becquerel, but they both measure the same parameter.
See Conversion Equivalence

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Conversion Equivalence

1 curie	=	3.7 x 1010 disintegrations per second
1 becquerel	=	1 disintegration per second
1 millicurie (mCi)	=	37 megabecquerels (MBq)
1 rad	=	0.01 gray (Gy)
1 rem	=	0.01 sievert (Sv)
1 roentgen (R)	=	0.000258 coulomb/ kilogram (C/kg)
1 megabecquerel (MBq)	=	0.027 millicuries (mCi)
1 gray (Gy)	=	100 rad
1 sievert (Sv)	=	100 rem
1 coulomb/ kilogram (C/kg)	=	3,880 roentgens

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Prefixes Often Used with SI Units

Multiple	Prefix	Symbol
1012	tera	T
109	giga	G
106	mega	M
103	kilo	k
10-2	centi	c
10-3	milli	m
10-6	micro	μ
10-9	nano	n

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Dose Unit Conversion Tool

Insert a number with up to 2 decimal points

Absorbed Dose

rad
centigray (cGy)
gray (Gy)
Convert Clear

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Dose Equivalent

rem
millisievert (mSv)
sievert (Sv)
Convert Clear

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Radioactivity Unit Conversion Tool

Insert a number with up to 2 decimal points
Results are expressed in E-notation*

curie (Ci)
becquerel (Bq)
millicurie (mCi)
megabecquerel (MBq)
Convert Clear

*E-notation examples:
3.05e+9 = 3.05 x 10⁹
7.26e-3 = 7.26 x 10^-3

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Exposure Unit Conversion Tool

Insert a number with up to 2 decimal points
Results are expressed in E-notation*

roentgen (R)
coulomb/kg (C/kg)
Convert Clear

*E-notation examples:
3.05e+9 = 3.05 x 10⁹
7.26e-3 = 7.26 x 10^-3

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Conversion Factors

To convert from	To	Multiply by
Curies (Ci)	becquerels (Bq)	3.7 x 1010
millicuries (mCi)	megabecquerels (MBq)	37
microcuries (μCi)	megabecquerels (MBq)	0.037
millirads (mrad)	milligrays (mGy)	0.01
millirems (mrem)	microsieverts (μSv)	10
milliroentgens (mR)	microcoulombs/kilogram (μC/kg)	0.258
To convert from	To	Multiply by
becquerels (Bq)	curies (Ci)	2.7 x 10-11
megabecquerels (MBq)	millicuries (mCi)	0.027
megabecquerels (MBq)	microcuries (μCi)	27
milligrays (mGy)	millirads (mrad)	100
microsieverts (μSv)	millrems (mrem)	0.1
microcoulombs/kilogram (μC/kg)	milliroentgens (mR)	3.88

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References

1. What is Radiation Dose? (2:03 min) (DOE/ORISE/REAC/TS)
2. Sievert (Wikipedia)
3. Explained: rad, rem, sieverts, becquerels, A guide to terminology about radiation exposure (MIT)
4. Measuring Radiation (NRC)

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