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Radioactivity Converter

Convert becquerel, curie, rutherford, and disintegrations per second for radiation measurements.

Tested tool guide Tested browser tools Checked August 16, 2026

What Radioactivity Converter does, with a checked example

These four units all measure the same quantity: radioactive activity, the rate at which atoms in a sample disintegrate. You enter a value with its unit and the tool returns the equivalent in every other unit. The conversions are fixed definitions, not measurements - a curie is exactly 3.7 x 10^10 becquerels and a rutherford exactly 10^6 becquerels - so the arithmetic is exact. Two things surprise people: becquerel and disintegration per second are the same unit under different names, and the curie is so large that real-world values are almost always written in millicuries, microcuries, or nanocuries, not whole curies.

Worked example

A concrete input and expected output from the current implementation.

Input

37 MBq

Expected output

1 mCi (0.001 Ci), 1000 uCi, 37,000,000 Bq, 37 Rd, 37,000,000 dps

One curie is exactly 3.7 x 10^10 Bq, so 37 MBq is 0.001 Ci, or 1 mCi, which is 1000 uCi. It is 37 rutherfords because a rutherford is exactly 10^6 Bq, and the becquerel and dps figures match because one becquerel is one disintegration per second by definition.

How the result is produced

1

Fixed conversion factors

The curie is defined as exactly 3.7 x 10^10 becquerels, the rutherford as exactly 10^6 becquerels, and one becquerel is one disintegration per second by definition. Each conversion is a single multiplication or division by one of these fixed factors, so the result is exact - nothing in the conversion introduces measurement uncertainty, and converting any unit to another and back returns the original value.

2

Metric prefixes and the 37 pattern

Activity values span many orders of magnitude, so the tool works with prefixes: kilobecquerel (10^3 Bq), megabecquerel (10^6 Bq), gigabecquerel (10^9 Bq), and on the curie side millicurie, microcurie, and nanocurie. The familiar ratio 37 keeps appearing because one curie is 3.7 x 10^10 Bq: one microcurie is exactly 37,000 Bq and one nanocurie is exactly 37 Bq.

Good uses

  • A calibration certificate or isotope order lists activity in millicuries; convert it to becquerels (or kBq, MBq) for a report, license form, or internal record kept in SI units.
  • A radioactive source specification quotes activity in curies; check it against a handling or shipping limit expressed in becquerels before accepting the source.
  • Older textbooks and papers measure activity in rutherfords, a unit you will not see on modern certificates; convert those values to becquerels to compare them with current measurements.

Limits and checks

  • Becquerel and disintegration per second are the same quantity: convert 500 Bq to dps and the tool returns 500. An unchanged number here is correct behavior, not a failed conversion.
  • The curie is huge. One curie is 3.7 x 10^10 Bq, so a value entered as plain curies converts to a staggeringly large becquerel count; laboratory quantities are millicuries, microcuries, and nanocuries. Confirm the prefix before trusting the figure.
  • Bq and Ci measure activity, not dose or exposure. Sievert, rem, and roentgen describe biological effect or exposure and depend on the isotope, its energy, and the geometry - no activity value converts into them through this tool.

Common questions

How many becquerels are in one curie?

Exactly 3.7 x 10^10. Because that figure is so large, values expressed in whole curies are rare in practice: one millicurie is 37 MBq, one microcurie is 37 kBq, and one nanocurie is 37 Bq. If a document quotes an activity in curies at all, a prefix is almost always intended.

Are becquerel and disintegrations per second really the same unit?

Yes, by definition: one becquerel is one disintegration per second, so this tool always returns the same number for both. The two names exist because the 15th General Conference on Weights and Measures adopted becquerel as the SI special name for the unit in 1975, while older documents still say disintegrations per second, or dps.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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