India, a developing country, shows that very few landfill sites are engineered landfills where municipal solid waste (MSW) is disposed of scientifically; the rest are open dumping where unscientific disposal occurs. During the biodegradation of MSW, landfill gases, mainly methane and CO2, emit into the atmosphere called landfill gas emissions (LFG). These LFG emissions are responsible for global warming and mostly depend on MSW’s composition and biodegradation process. The main primary methane landfill gas has a huge potential for energy production with the proper available technology. The LandGEM is a mathematical model used to estimate landfill gases more accurately and uses input data. This study estimates total landfill gases and methane generation for Nashik city, Maharashtra, India, using the LandGEM model to suit the Indian climatic conditions. According to the results, methane generation was calculated from the years 2000 to 2021, i.e., a partial closure period of landfill and estimated up to 2051. The LFG gas emissions are predicted based on waste received by the landfill out of the total solid waste generated. The study's main objective is to formulate the criteria required for the LandGEM model and to estimate the LFGs for the waste composition of the Nashik municipal landfill site, Maharashtra, India, which has not been investigated yet. The decay rate for Nashik city is evaluated and found to be k = 0.0481, which is considered suitable for Indian climatic conditions. The total amount of methane gas production, estimated at 7816m3/year in 2021 at the partial closure of the landfill, increased to 13,882 m3/year up to 2051. This study is helpful to practitioners and experts in providing landfill gas collection systems and greenhouse gas emission control in the coming years. The efficient utilization of landfills can help manage waste sustainably and indirectly contribute to reducing the greenhouse effect.