Ci → Bq
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Curie to Becquerel (Ci → Bq) calculator converts a historical unit of radioactivity into the International System of Units (SI). The Curie (Ci) was widely used in the past, while the Becquerel (Bq) represents one disintegration per second. The formula applied is 1 Ci = 3.7 × 10¹⁰ Bq. This tool is useful in nuclear medicine, geology, and radiological research where modern standards are required.
To convert, simply input the value in Curie and the calculator will automatically multiply it by 37 billion. Example: 2 Ci equals 74 × 10¹⁰ Bq. This conversion is essential for scientific reports or when working with equipment requiring measurements in Bq. Note: Curie is an outdated unit in modern contexts but remains in historical documents.
The accuracy of the conversion relies on the fixed formula of 3.7 × 10¹⁰ Bq/Ci, an internationally recognized standard. Avoid using this tool for critical measurements without cross-verifying data through additional methods. Also, do not confuse radioactivity activity with absorbed dose, which is measured in grays (Gy).
Frequently asked questions
Why is the conversion factor 3.7 × 10¹⁰?
This is an international definition: 1 Curie equals the activity of 1 gram of radium-226. The Becquerel measures one disintegration per second, resulting in 3.7 × 10¹⁰ Bq/Ci.
When should I use this calculator?
Use it to update historical scientific reports, work with equipment requiring Bq, or compare data between past and modern contexts.
Is there a Bq → Ci converter available?
Yes, simply divide the Bq value by 3.7 × 10¹⁰. Some advanced online tools include this functionality.
Is this conversion accurate for medical measurements?
No. In medical contexts, follow specific protocols, as radioactive activity applications vary by procedure and equipment.