Convert radioactivity between Bq, kBq, MBq, GBq, Ci, mCi, and rutherford, then compare SI and legacy activity scales on one sheet.
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Radiology Reference
A radiation activity converter is useful when source strength is reported in becquerels in one document and curies in another. This page keeps the quantity boundary explicit: activity counts nuclear decays per unit time, and it does not on its own describe dose, exposure in air, or biological effect.
Radiation activity measures how many nuclear transformations occur in a given time interval. In SI, the unit is the becquerel, defined as one disintegration per second.
That makes activity different from dose or exposure. A highly active source does not automatically imply a particular dose to a person unless geometry, shielding, time, energy, and pathway are also known.
Becquerel is the international SI unit, but many U.S. and legacy references still cite curies or millicuries. Older literature may also mention the historical rutherford, defined as one million disintegrations per second.
A converter is useful because those labels remain common in source documentation, procurement sheets, and educational material even though SI reporting is preferred.
1 Ci = 3.7 × 10^10 Bq
Standard activity relationship between the legacy curie and the SI becquerel.
1 Rd = 10^6 disintegrations/s = 1 MBq
Historical definition of the rutherford as a legacy activity unit.
People often use source strength as a shorthand for risk, but that shortcut can be misleading. The same activity can lead to very different exposures depending on radiation type, energy, distance, containment, and time.
This converter therefore treats activity as its own unit problem rather than pretending it can replace a shielding, exposure, or dose calculation.
Frequently asked questions
1 curie equals 37 billion becquerels, or 3.7 × 10^10 Bq.
Rutherford is a historical activity unit defined as one million disintegrations per second. It is mainly useful when reading older scientific literature and should be treated as a legacy label.
No. Dose depends on more than source activity. Distance, shielding, radiation type, energy, exposure duration, and route all matter.
Because curie notation is still encountered in U.S. practice, legacy records, and older references. A converter remains helpful when translating that material into SI reporting.
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