There is no direct method of conversion from Microsieverts Per Hour (μSv/hr) to Counts Per Minute (CPM). This study presents an evaluation of approximation methods of going about this conversion. In this study, indoor and outdoor background gamma radiation measurements are carried out using Fluke Biomedical 451 ion Chamber Survey Meter. A cogitate look at the survey Meter’s manual shows that the specifications are: Radiation Detected – Alpha above 7.5 MeV, Beta above 100 keV and Gamma above 7 keV; Operating Ranges – 0 to 50 μSv/hr, 0 to 500 μSv/hr, 0 to 5 mSv/hr, 0 to 50 mSv/hr, 0 to 500 mSv/hr and Accuracy – ± 10 % of reading between 10 % and 100 % of full – scale indication on any range,exclusive of energy response (calibration source is Cs–137). Relevant literatures have shown that for radiation survey meters whose calibration source is Cs–137, the conversion factor from μSv/hr to CPM is around 1 μSv/hr per 120 CPM while those whose calibration source is Co–60, the conversion factor from μSv/hr to CPM is around 1 μSv/hr per 108 CPM. In this study, the calculated Annual Effective Dose (AED) of background gamma radiation levels ranges from 0.925 to 2.943 mSv/yr for the indoor measurement and from 0.289 to 0.560 mSv/yr for the outdoor measurement. The ratio of indoor to outdoor dose rate values in μSv/hr is computed for each corresponding reading from which the mean indoor – to – outdoor ratio for the readings is computed for comparison with the 1.5 set by UNSCEAR (UNSCEAR, 2008). The use of CPM in radiation monitoring, environmental monitoring, health physics, quality control and the health implications of the results obtained in this study are discussed.