For those needing portability, Rad Pro for Desktop works with Windows 8.1/10 tablets. Will not work with Surface tablets running Windows RT.
Select Distance Units
Select Exposure Rate Units
Calculated Final Dose-Rate
Enter Starting Dose-Rate
Enter Ending Distance
Enter Starting Distance
Inverse Square Law Calculations
This calculator was first developed for students to demonstrate the inverse square law principal from radiation physics. As it turns out, it does get quite a bit of use in the field. The ALARA calculator on this site is more comprehensive, but sometimes this calculator is all that is required for a simple distance to dose-rate relationship demonstration.