Radiation unit converter — sievert, rem, gray, rad, becquerel, curie

How to use the radiation converter

1. Type the number in Value.
2. Choose its unit in From. Every option shows its group in brackets, for example “rem (dose equivalent)” or “curie (Ci) (activity)”.
3. Choose a unit from the same group in To. The default converts 1 millisievert (mSv) to rem.
4. Read the answer and the table of every unit in that group. If you pick units from two groups, you get a short explanation instead.

What it does and when to use it

Radiation figures appear in medical reports, nuclear medicine orders, lab safety sheets, old textbooks and news stories, often in a mix of modern SI units and older ones. A US report might give millirem while a European one gives microsieverts, and a radiopharmacy might order in millicuries while the label says megabecquerels.

The tool has four groups:

How it works

Within a group, each unit is a multiple of the SI unit. The tool multiplies by the From factor and divides by the To factor, and shows 12 significant figures. All four older units are exact by definition, and NIST lists the same factors.

Across groups there is no fixed factor, so the tool returns a message. Sievert and gray get the special note about the radiation weighting factor.

Worked examples

A dose in a US report. 2.4 mSv = 240 millirem (0.24 rem).

A nuclear medicine vial. 500 MBq = 13.5135135135 millicurie (mCi), or 13,513.5 µCi.

Mixing groups. 10 mGy to mSv returns a message about the radiation weighting factor rather than a number.

Limits and tips

• Check the prefix. mSv (milli, 10⁻³) and µSv (micro, 10⁻⁶) differ by a factor of 1,000. Many dosimeters show µSv/h, a dose rate. Convert the number here, but remember the “per hour”.
• Rates work too. Units per hour convert the same way, because the time part does not change. For time units on their own, use the time converter.
• For large or tiny numbers, the scientific notation calculator helps you read long results such as 1 Ci shown as 37,000,000,000 Bq. For energy units such as electronvolts, use the energy converter.