The prediction of methane emissions into planned longwalls becomes more and more important in conditions of increasing output concentration and rising methane saturation of the deposit along with the exploitation depth.The calculated values of predictions of methane emissions at the life of face (in terms of distance) of planned longwalls have a bearing on the selection of an appropriate ventilation system and scope of applied prevention including methane drainage.The accuracy of calculated predictions of methane emissions constitutes the basic link at the stage of longwall planning.The divergences between the predicted and real methane emissions into longwalls during their exploitation have influence on the safety and economic aspects resulting from incorrect assessment of the methane hazard level at the planning stage.Appropriate planning of the longwall length has priority significance for safe exploitation conducting in strongly gassy seams.The article presents for variable longwall length (in variants) the method of calculation of initial quantities for the calculation of predictions,having a bearing on the accuracy of obtained results,and in consequence on the way of planning and conditions of safe exploitation.