Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Rad to Gray
Convert rad to Gy instantly, then review the formula, assumptions, and rounding guidance.
Radiation unitsInstant result
Decimals
Formula result = input × 0.01 ÷ 1. 1 rad = 0.01 Gy
Common examples
One value, several units
Gray0.01 Gy
Milligray10 mGy
Joules per kilogram0.01 J/kg
Conversion table
| rad | Gy |
|---|---|
| 1 rad | 0.01 Gy |
| 2 rad | 0.02 Gy |
| 5 rad | 0.05 Gy |
| 10 rad | 0.1 Gy |
| 25 rad | 0.25 Gy |
| 50 rad | 0.5 Gy |
| 100 rad | 1 Gy |
Conversion chart
1 rad0.01 Gy
5 rad0.05 Gy
10 rad0.1 Gy
25 rad0.25 Gy
50 rad0.5 Gy
Worked example
1 gray equals 100 rad.
Unit definition
Rad (rad) One rad equals 0.01 gray.
Unit history
Rad is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert rad to gray.
3. Convert the base value to Gy and apply your display precision.
Understand the result before using it
Rad to Gray converts a value measured in Rad (rad) into the equivalent value in Gray (Gy). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 0.01 ÷ 1
Assumptions
- Rad and Gray represent the same absorbed dose quantity.
- The input is expressed in rad; the output is expressed in Gy.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 rad = 0.01 Gy. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a rad measurement in a document that expects Gy.
- Compare a rad value with a value reported in gray.
- Check the rad-to-Gy arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Absorbed dose, equivalent dose, and activity describe different radiation quantities and are not interchangeable.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Rad to Gray?
result = input × 0.01 ÷ 1 Using the displayed relationship, 1 rad equals 0.01 Gy.
How many Gray are in one Rad?
One Rad is 0.01 Gray. The displayed digits may be rounded.
Can I reverse the rad to Gy conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts Gy back to rad.
Is the Rad to Gray result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.