Cpm, or counts per minute, and mrem, or millirem, are units that are used to measure the amount of radiation that has been absorbed. Low levels of radiation are common in many parts of the world, and most of these areas are not harmful. For example, you would absorb one millirem of radiation if you lived in Atlanta for three days or Denver for two days. Converting a cpm figure to an mrem figure is easy once you know the conversion factor to use.

Write down your cpm figure. As an example, you have a reading of 30 cpm.

Multiply the cpm reading by 0.001 to convert the figure to millirems per hour. Using the example of 30 cpm, if you multiply 30 by 0.001, you get 0.03. Therefore, 30 cpm is equal to 0.03 mrem/h.

Multiply the result from Step 2 by 24 to determine the millirems per day absorbed. Using the example, if you multiply 0.03 by 24, you get 0.72. Therefore, 30 cpm is equal to 0.72 mrem/day.

Multiply the result from Step 3 by 365 to determine the millirems per year absorbed. Using the example, multiplying 0.72 by 365 produces 262.8. Therefore, 30 cpm is equal to 262.8 mrem/year.