Enter your Activity Value and choose your From Unit and To Unit — becquerel, curie, or any other radioactivity unit — and this Activity Calculator gives you the Converted Value alongside the Conversion Factor and Scientific Notation for when the numbers get gloriously unwieldy.
Converted Value
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Conversion Factor
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Scientific Notation
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Becquerel (Bq) is the SI unit for radioactivity, measuring one disintegration per second. Curie (Ci) is an older unit equal to 3.7 × 10¹⁰ disintegrations per second, originally based on the activity of 1 gram of radium-226.
To convert Curie to Becquerel, multiply by 3.7 × 10¹⁰ (37,000,000,000). For example, 1 Ci = 37 GBq. The conversion factor is based on the original definition of the Curie unit.
Common multiples include kilobecquerel (kBq = 10³ Bq), megabecquerel (MBq = 10⁶ Bq), gigabecquerel (GBq = 10⁹ Bq), and terabecquerel (TBq = 10¹² Bq). These are used depending on the activity level being measured.
Different units evolved for practical reasons. The Curie was historically used and is still common in some fields, while the Becquerel is the modern SI standard. Multiples and submultiples help express very large or small activity values conveniently.
Activity levels vary greatly depending on context. Natural background radiation is typically picocuries per liter for radon, while medical isotopes may be in millicuries, and nuclear reactor materials can be in the curie or terabecquerel range.
The conversions are based on exact defined relationships between units. The Curie is defined as exactly 3.7 × 10¹⁰ Bq, making conversions mathematically precise with no approximation involved.