燃气是可用作燃料的气体，可指：

• 石油气
• 煤气
• 天然气
• 可燃气体
• 合成气
• 木煤气
• 生物气体

虽然「石油气」很多时俗称「煤气」（例如「煤气瓶」其实指液化石油气瓶），但两者成份不同，炉具并不通用。

Fuel gas is any one of a number of fuels that under ordinary conditions are gaseous. Many fuel gases are composed of hydrocarbons (such as methane or propane), hydrogen, carbon monoxide, or mixtures thereof. Such gases are sources of potential heat energy or light energy that can be readily transmitted and distributed through pipes from the point of origin directly to the place of consumption.