This study is to determine guideline to reduce carbon footprint for organization of medium and small hotels in Thailand using the Carbon Footprint for Organization (CFO) according to Thailand Greenhouse Gas Management Organization (Public Organization). Conducting with 2 represented medium and small hotels the results showed that the overall carbon footprint average of 2013 was 553t.Co2-e. Considering concentration index by number of guestrooms the carbon footprint was 18.81 kg.Co2e/room-night 221.16 kg.Co2-e/m2 by total floor area and 11.65kg.Co2- e/personby guest. The dominant source of carbon footprint was use of electricity 465t.Co2-e(83.06%). Base on this assessment to use of air conditioning was 60.09 % water heater 17.64 % lighting equipment 15.05 % and other 7.22 % of total electricity used. Therefore guidelines for carbon footprint reducing of the representative hotel were to use technology to reduce electricity consumption for air conditioning water heater and lighting respectively. Based Approach to Reducing Carbon Footprint found that small and medium sized hotels can reduce emissions per year 24.87 t.CO2-e representing the ability to reduce greenhouse gas emissions by up to 4.49% or financial projections be able to save money 171.202 baht per year.