Find out how long your propane tank will last based on its size and your appliance's usage rate.
Propane holds a predictable amount of energy per gallon (about 91,500 BTU), so tank life comes down to comparing that total energy supply against your appliance's hourly burn rate and daily usage.
Days of Supply = (Tank Size (gal) × 91,500 BTU) ÷ (Appliance BTU/hr × Hours Used per Day)
A 100-gallon tank running a 30,000 BTU/hr appliance 4 hours/day lasts about 76 days, or roughly 2.5 months.
Tank capacity divided by your appliance's BTU consumption rate per hour.
A common 20lb tank holds about 4.7 gallons, though sizes vary widely.
Higher BTU appliances burn propane faster, reducing how long a tank lasts.