In the present work, different methods were used to calculate the atomic cross-sections, electronic cross-sections, effective Z, effective electron density and mean free path for the Bi4Ge3O12 gamma ray detector popularly known as BGO detector. The methods are Direct method using attenuation coefficients evaluated using WinXCom software, the others are DirectZeff software, AutoZeff software, XMuDat software and still another method used is Power law method. The results of first two methods i. e. Direct method and Direct Zeff software are in good agreement with each other. These results are also reproduced nicely by power law method. The Zeff predicted by AutoZeff are too large compared with our predictions and XMuDat predicts too small value for Zeff