Kerosene heaters come in different sizes of tanks, while the larger one with a full tank can easily hold 1.2 liters. This fuel tank will make the heater run for up to 14 hours. Simply, this 1.2-gallon fuel tank will provide warmth for 14 hours, which means 1 gallon of kerosene will run a heater for 11.6 hours. Keep in mind that the heater will burn the fuel based on its settings. For instance, if kept heater at a high-temperature setting, then the rate of fuel consumption is high. Ensure to use high-quality kerosene, such as a 1-K grade for maximum efficiency rather than low-grade fuels available at low prices.