For those needing portability, Rad Pro for Desktop works with Windows 8.1/10 tablets. Will not work with Surface tablets running Windows RT.
Dose-Rate
Distance
Calculate?
Select Distance Units
Select Exposure Rate Units
mR/hr
Feet
Feet
mR/hr
Calculated Final Dose-Rate
Enter Starting Dose-Rate
Enter Ending Distance
Enter Starting Distance
Inverse Square Law Calculations
Feet
Meters
Inches
R/hr
mR/hr
uR/hr
Sv/hr
mSv/hr
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.