A 20 lb propane tank holds approximately 430,000 BTUs of energy.

A standard 20-pound propane tank contains about 430,000 BTUs of energy. This amount of propane can power various appliances for different durations depending on their BTU consumption rate. For example, a typical propane grill burner uses about 30,000 BTUs per hour, meaning a full tank could run for approximately 14 hours on high heat.

BTU Content Comparison for Common Propane Tank Sizes

Tank Size Propane Weight Approximate BTUs Runtime on 30,000 BTU/hr appliance
20 lb 20 lbs 430,000 14.3 hours
30 lb 30 lbs 645,000 21.5 hours
40 lb 40 lbs 860,000 28.7 hours

Factors Affecting BTU Output and Usage

  • Temperature: Propane pressure and efficiency decrease in cold weather
  • Tank fill level: Tanks are typically filled to 80% capacity for safety
  • Appliance efficiency: Different appliances use propane at varying rates
  • Regulator condition: A faulty regulator can reduce BTU delivery

Calculating Runtime for Your Appliance

To determine how long your 20 lb propane tank will last:

  1. Find your appliance's BTU rating
  2. Divide 430,000 by the appliance's BTU rating
  3. The result is approximate runtime in hours

For example: A 60,000 BTU patio heater would run for about 7.2 hours on a full tank (430,000 ÷ 60,000 = 7.17).