Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Gray to Rad
Convert Gy to rad instantly, then review the formula, assumptions, and rounding guidance.
Radiation unitsInstant result
Decimals
Formula result = input × 1 ÷ 0.01. 1 Gy = 100 rad
Common examples
One value, several units
Milligray1,000 mGy
Rad100 rad
Joules per kilogram1 J/kg
Conversion table
| Gy | rad |
|---|---|
| 1 Gy | 100 rad |
| 2 Gy | 200 rad |
| 5 Gy | 500 rad |
| 10 Gy | 1,000 rad |
| 25 Gy | 2,500 rad |
| 50 Gy | 5,000 rad |
| 100 Gy | 10,000 rad |
Conversion chart
1 Gy100 rad
5 Gy500 rad
10 Gy1,000 rad
25 Gy2,500 rad
50 Gy5,000 rad
Worked example
1 gray equals 100 rad.
Unit definition
Gray (Gy) One gray equals 1 gray.
Unit history
Gray 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 Gy to gray.
3. Convert the base value to rad and apply your display precision.
Understand the result before using it
Gray to Rad converts a value measured in Gray (Gy) into the equivalent value in Rad (rad). 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 × 1 ÷ 0.01
Assumptions
- Gray and Rad represent the same absorbed dose quantity.
- The input is expressed in Gy; the output is expressed in rad.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 Gy = 100 rad. 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 Gy measurement in a document that expects rad.
- Compare a gray value with a value reported in rad.
- Check the Gy-to-rad 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 Gray to Rad?
result = input × 1 ÷ 0.01 Using the displayed relationship, 1 Gy equals 100 rad.
How many Rad are in one Gray?
One Gray is 100 Rad. The displayed digits may be rounded.
Can I reverse the Gy to rad conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts rad back to Gy.
Is the Gray to Rad 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.