1 cubic foot of gas contains on AVERAGE 1,000 Btu
1.5 million ft3 = 1,500,000,000 btu
100,000 BTU = 1 Therm
1,500,000,000/ 100,000 = 15,000 therms
Appliance Average Therms Used
Water Heater 24 therms/month
Range 2 therms/month
Dryer 5 therms/month
Gas Grill 0.23 therms per use
Gas Logs 3 therms every 8 hours
-- according to Atlanta Gas Light Company