Curie to Becquerel Converter (Ci ⇄ Bq)
Convert radioactivity values between the older curie (Ci) unit and the SI unit becquerel (Bq). Handy for nuclear medicine reports, radiation protection notes, and scientific papers.
1 Ci = 3.7 × 10¹⁰ Bq
1 Bq = 1 decay/second
This tool converts only activity units. It does not calculate radiation dose (Gy, Sv) or exposure.
Conversion formulas
1 Ci = 3.7 × 10¹⁰ Bq
1 mCi = 3.7 × 10⁷ Bq
1 µCi = 3.7 × 10⁴ Bq
1 Bq = 2.7027 × 10⁻¹¹ Ci
Bq = Ci × 3.7e10
The curie was defined from the activity of 1 gram of radium-226; the becquerel is the SI derived unit equal to one nuclear decay per second.
Quick Ci → Bq table
| Ci | Bq | MBq |
|---|
Rounded for readability.
Important note
These are unit conversions only. For patient administration, workplace limits, transport or waste classification, follow your regulator (IAEA, ICRP, national authority) and medical physics team.
Why convert between curie and becquerel?
Older documents, U.S. procedures or legacy nuclear instrumentation often still quote activity in curies or millicuries. Modern international standards, EU directives and most scientific journals expect becquerels or multiples (kBq, MBq, GBq). A precise converter helps you keep consistency in reports.
Typical values
- Small lab sources (check): tens of kBq to a few MBq
- Nuclear medicine diagnostic doses: some hundred MBq (varies with radionuclide)
- Industrial sources: GBq and above
FAQ
1. What is the smallest unit I can enter?
You can enter down to nCi on the left side, or directly in Bq on the right side. The calculator will scale up/down.
2. Can I get pCi (picocurie)?
pCi is common in environmental monitoring (water, air). To convert pCi/L → Bq/m³, you usually need an extra step for volume. This page focuses on activity only.
3. Are these factors exact?
Yes, the exact definition is 1 Ci = 3.7 × 10¹⁰ Bq. We use this in the calculations.
Formula (LaTeX) + variables + units
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1 Ci = 3.7 × 10¹⁰ Bq 1 mCi = 3.7 × 10⁷ Bq 1 µCi = 3.7 × 10⁴ Bq 1 Bq = 2.7027 × 10⁻¹¹ Ci Bq = Ci × 3.7e10
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.