What is a becquerel (Bq)?

A becquerel is the SI unit of radioactivity, equal to one nuclear disintegration per second. It replaced the curie as the standard unit of activity in the International System of Units (SI).

What is a curie (Ci)?

A curie is a non-SI unit of radioactivity equal to 3.7 × 10^10 disintegrations per second, originally defined as the activity of 1 gram of radium-226. It is still widely used in nuclear medicine and older North American literature.

How do you convert becquerels to curies?

Divide the becquerel value by 3.7 × 10^10. For example, 37 GBq = 37 × 10^9 Bq ÷ 3.7 × 10^10 = 1 Ci. The conversion is exact by definition.

What are common becquerel prefixes?

Common SI prefixes are: TBq (terabecquerel, 10^12 Bq), GBq (gigabecquerel, 10^9 Bq), MBq (megabecquerel, 10^6 Bq), kBq (kilobecquerel, 10^3 Bq), Bq (base unit), and mBq (millibecquerel, 10^-3 Bq). Nuclear medicine most often uses MBq and GBq.

What is 1 becquerel equal to in curies?

1 Bq = 1 / (3.7 × 10^10) Ci ≈ 2.7027 × 10^-11 Ci, or about 27 picocuries (pCi). Conversely, 1 Ci = 37 GBq.

Which industries use both becquerels and curies?

Nuclear medicine (PET, SPECT, brachytherapy), radiation oncology, health physics, nuclear power plant safety, and industrial radiography all measure source activity. The becquerel is the current SI standard worldwide; the curie is common in legacy North American documents.

Becquerel to Curie Converter

Name: Becquerel to Curie Converter
Availability: InStock
Author: Nham Vu

Enter a value in becquerels (any SI prefix) and get the exact equivalent in curies — 1 Ci = 3.7 × 10^10 Bq.

Becquerel to Curie Converter

Becquerel Prefix

Radioactivity Value

Common Activity Reference Points

Click a row to load it

Context	Input (Bq)	Result (Ci)

Summary

Enter a value in becquerels (any SI prefix) and get the exact equivalent in curies — 1 Ci = 3.7 × 10^10 Bq.

How it works

Select the becquerel prefix (TBq, GBq, MBq, kBq, Bq, or mBq) from the dropdown.
Enter the radioactivity value in the input field.
The equivalent activity in curies appears instantly in the result panel.
The conversion formula is displayed below the inputs.
Click any row in the reference table to load that value into the converter.

Use cases

Convert SI becquerel measurements to curie values required by legacy documentation.
Cross-reference isotope activity from nuclear medicine reports in familiar curie units.
Translate published research data from becquerels to curies for North American audiences.
Verify source-activity figures across unit systems for radiation safety compliance.
Convert equipment calibration values from modern SI to legacy curie notation.
Study or teach radioactivity unit conversions in physics or health physics courses.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu