Radiation Activity Converter

Radioactivity, or activity, is how many atoms of a radioactive substance decay each second. Its SI unit is the becquerel (Bq), one decay per second. The older unit is the curie (Ci), the activity of one gram of radium-226: 1 Ci = 3.7 × 10¹⁰ Bq, exactly.

The becquerel is tiny, so activities are usually in kBq, MBq or GBq. For a sense of scale: a banana holds about 15 Bq of natural potassium-40, an adult's body about 4,000–5,000 Bq of it, and a medical scan uses hundreds of MBq.

Activity says how many atoms decay, not how much radiation a person receives. The dose is converted in the Radiation - Absorbed Dose Converter.

How to convert becquerels and curies

Type a value into any field, and every other unit is calculated at once. For example, a 370 MBq dose for a medical scan:

1. In millicuries: a millicurie is 37 MBq.

   370 / 37 = 10 mCi

2. In becquerels: multiply by 1,000,000.

   370 * 1,000,000 = 370,000,000 Bq

Common conversions

Radioactivity units

• Becquerel (Bq): The becquerel is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relating to human health this is a small quantity, and SI multiples of the unit are commonly used.

• Kilobecquerel (kBq): 1 kBq = 10^3 Bq (1,000 Bq)

• Megabecquerel (MBq): 1 MBq = 10^6 Bq (1,000,000 Bq)

• Gigabecquerel (GBq): 1 GBq = 10^9 Bq (1,000,000,000 Bq)

• Terabecquerel (TBq): 1 TBq = 10^12 Bq (1,000,000,000,000 Bq)

• Millibecquerel (mBq): 1 mBq = 10^(-3) Bq (0.001 Bq)

• Curie (Ci): The curie is a unit of radioactivity, representing 3.7 * 10^10 disintegrations per second, or 1 Ci = 3.7 * 10^10 Bq (37,000,000,000 Bq).

• Kilocurie (kCi): 1 kCi = 10^3 Ci = 3.7 * 10^13 Bq (37,000,000,000,000 Bq).

• Millicurie (mCi): 1 mCi = 10^(-3) Ci = 3.7 * 10^7 Bq (37,000,000 Bq).

• Microcurie (μCi): 1 μCi = 10^(-6) Ci = 3.7 * 10^4 Bq (37,000 Bq).

• Nanocurie (nCi): 1 nCi = 10^(-9) Ci = 3.7 * 10^1 Bq (37 Bq).

• Picocurie (pCi): 1 pCi = 10^(-12) Ci = 3.7 * 10^(-2) Bq (0.037 Bq).

• Rutherford (rd): The rutherford is a unit of radioactivity, representing one million nuclei decay per second, or 1 rd = 1,000,000 Bq.

• One/second (1/s): This is an equivalent to the Becquerel, representing one decay per second.

• Disintegrations/second: The number of radioactive disintegrations occurring in one second. This is also an equivalent to the Becquerel.

• Disintegrations/minute: This is the number of radioactive disintegrations occurring in one minute and is equal to 1/60 Bq.

Frequently asked questions

What is a pCi/L of radon?

Radon in homes is measured in picocuries per liter of air in the US, and in becquerels per cubic meter elsewhere: 1 pCi/L = 37 Bq/m³. The US EPA recommends action at 4 pCi/L, about 150 Bq/m³.