Radiation Converter Calculator

Radiation units describe different things, and mixing them can create dangerous misreadings. This calculator follows the form’s calculation exactly: it converts activity between Becquerel (Bq) and Curie (Ci), reports Gray (Gy) as absorbed dose only, and converts equivalent dose between Sievert (Sv) and rem. Enter a nonnegative Value, choose the Unit, and read only the compatible results shown in the panel.

The important point is that radiation is not one quantity. Activity describes how many nuclear transformations occur per second in a source. Absorbed dose describes energy deposited in material per unit mass. Equivalent dose adjusts absorbed dose for radiation type to better represent biological effect. The calculator keeps those categories separate. It does not convert Bq to Gy, Bq to Sv, Gy to Sv, or Gy to rem, because those relationships require physical and biological information that a simple unit dropdown does not have.

Quantities handled by the form

The form also contains a useful warning in its note: activity, absorbed dose, and equivalent dose are not directly convertible between each other. That guardrail is intentional. A source can have high activity but low dose at a distance, and the same absorbed dose in gray can imply different equivalent doses depending on the radiation weighting factor.

Exact formulas used

For activity, the calculator converts the selected value into becquerels:

$\text{activity in Bq} = \text{value} \text{ } \times \text{ } \text{activity factor}$

The factors are 1 for Bq and 37,000,000,000 for Ci. The calculation is:

$\text{Ci} = \frac{\text{Bq}}{37{,}000{,}000{,}000}$

For equivalent dose, the calculator converts to sieverts first. The factors are 1 for Sv and 0.01 for rem:

$\text{equivalent dose in Sv} = \text{value} \text{ } \times \text{ } \text{dose factor}$

$\text{rem} = \frac{\text{Sv}}{0.01}$

For gray, the form does not apply a cross-unit formula. It rounds the gray value to four decimal places and labels it absorbed dose.

Examples

Activity example: convert 0.002 Ci. The source factor for Ci is 37,000,000,000:

$0.002 \text{ } \text{Ci} \text{ } \times \text{ } 37{,}000{,}000{,}000 = 74{,}000{,}000 \text{ } \text{Bq}$

The calculator reports 74,000,000 Bq and 0.002 Ci in the activity results. It does not show Gy, Sv, or rem for that input.

Equivalent dose example: convert 0.05 Sv. The source factor for Sv is 1, so the value in sieverts stays 0.05. The rem result is:

$\frac{0.05}{0.01} = 5$

The calculator reports 0.0500 Sv and 5.0000 rem. Absorbed dose example: enter 1.23456 Gy and the form displays absorbed dose as 1.2346 Gy after rounding. It does not convert that gray value to rem or sievert.

Domains and careful interpretation

Health physics and radiation protection use all three quantity types, but for different tasks. Activity helps describe radioactive material or contamination. Absorbed dose helps describe energy deposited in tissue, detectors, or materials. Equivalent dose helps compare biological effect across radiation types. Keeping the categories separate helps prevent a numeric conversion from being mistaken for a risk assessment.

Medical imaging and therapy may use radiation quantities under controlled protocols, but this page is not medical advice. It cannot interpret a scan, plan a treatment, judge occupational exposure, or evaluate symptoms. If a radiation exposure or medical result concerns you, consult qualified professionals.

Environmental monitoring and emergency response often involve dose rate, contamination surveys, isotope identification, shielding, distance, and time. Those calculations require instruments, procedures, and regulations. This page only formats compatible unit conversions once the correct quantity is known.

Pitfalls

• Do not convert Bq to Sv by a fixed factor. Source geometry, isotope, pathway, and time matter.
• Do not treat Gy and Sv as always equal. Gray is absorbed dose; sievert is weighted equivalent dose.
• Do not look for rad in the calculator. The calculator does not support it, even though rad is a known older absorbed-dose unit.
• Do not use the output to decide whether an exposure is safe. The result is a unit conversion, not a radiation survey, diagnosis, or regulatory decision.

Related tools can help with surrounding physics units: the energy converter for joules, the frequency converter for becquerel-as-per-second context, and the length converter if a separate shielding or distance note arrives in mixed length units.

Accuracy and limits

The numerical result is only as reliable as the entered measurements and the stated physical assumptions. A unit change does not determine density, concentration, geometry, reference pressure, efficiency, or safety. Preserve extra digits during intermediate work, round only for the final use, and confirm consequential decisions against the governing label, specification, or professional method.

Sources

• EPA, Radiation Terms and Units — definitions for Bq, Ci, Gy, Sv, rem, and related radiation quantities.
• EPA, Radiation Health Effects — overview of radiation health considerations and dose context.
• NIST, Guide for the Use of the International System of Units — SI and non-SI unit usage guidance.
• BIPM, SI base units — international SI reference background.