Radioactivity Converter

Convert activity of a radionuclide values among common SI, metric and customary units. Activity describes nuclear transformations per second. One becquerel is one transformation per second; one curie is exactly 3.7×10¹⁰ Bq.

ValueEnter zero or a positive value; scientific notation is accepted.Convert fromBecquerel (Bq)Kilobecquerel (kBq)Megabecquerel (MBq)Gigabecquerel (GBq)Curie (Ci)Millicurie (mCi)Microcurie (µCi)Convert toBecquerel (Bq)Kilobecquerel (kBq)Megabecquerel (MBq)Gigabecquerel (GBq)Curie (Ci)Millicurie (mCi)Microcurie (µCi)

Convert

Converted value37000 MBq

SI-base value3.7e+10 Bq

Multiply by37000

The displayed results apply to the default example. Enable JavaScript to convert other values.

How to use this converter

1. Enter the activity of a radionuclide value.
2. Select its current unit and the unit you want.
3. Select Convert. The page shows the converted value, the SI-base value and the direct multiplication factor.

Conversion formula

Converted value = entered value × source-to-SI factor ÷ target-to-SI factor.

Every option is represented by its factor to becquerel (Bq). This one-base method keeps reciprocal conversions consistent. Calculations run in your browser, and old results are hidden when an input changes or validation fails.

Worked example

Convert 1 Ci to MBq. Multiply by 37000; the result is 37000 MBq. The same input equals 3.7e+10 Bq in the SI-base unit.

Accuracy and limitations

Activity is not absorbed dose or exposure risk. Risk depends on radionuclide, radiation type, pathway, time, distance and shielding; use radiation-safety professionals.

The calculator retains more digits internally than it displays. Round the final value to the precision supported by your measurement. Very large and very small answers may use scientific notation.

Frequently asked questions

Does a higher becquerel value always mean a higher dose?

No. Activity counts transformations; dose depends on energy, radiation type, exposure geometry and biological uptake.

Can I reverse the conversion?

Yes. Swap the From and To selections. Because both units use the same SI base, the reverse factor is the reciprocal of the forward factor.

Why was my entry rejected?

Use digits with an optional decimal point or scientific notation. Blank values, commas, fractions, words and non-finite entries are rejected. Negative values are rejected because this converter treats the quantity as a magnitude.

Review notes and sources

Reviewed October 4, 2026. The conversion factors, default example, zero or signed boundary behavior, invalid-input handling and recovery after an error were checked. Factors follow SI definitions and published conversion guidance from the NIST Guide to the SI and the BIPM SI Brochure. Explanations and examples are original.

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