How long does propane last? It is one of the first things homeowners ask when a new tank goes in, and one of the last things they think about until the gauge drops in January. Propane itself never goes bad in the tank, so the real question is how long a full tank will keep your home running. That depends on three things: how much propane your tank actually holds, which appliances run on it, and how cold the winter gets.
How long does propane last: the short answer
There is no single number, because a tank that runs only a range and a fireplace might last a year, while the same tank heating a drafty farmhouse could run low in a few weeks of hard cold. To estimate your own usage:
- Start with usable gallons. Propane tanks are filled to about 80% of their listed capacity, so a 500-gallon tank holds about 400 gallons when full.
- Find each appliance’s Btu rating. It is on the appliance’s data plate or in the owner’s manual.
- Convert Btu to gallons. A gallon of propane contains about 91,452 Btu, according to the U.S. Energy Information Administration. Divide an appliance’s hourly Btu input by 91,452 to get gallons per hour at full burn.
- Multiply by run time. Your furnace does not run nonstop, so estimate the hours it actually runs on a typical day.
Propane tank sizes and usable gallons
| Tank size | Usable gallons (at 80%) | Typical use |
|---|---|---|
| 120-gallon vertical | About 100 | A single appliance or small demand, such as a range or water heater |
| 150-gallon | About 120 | Cooking, water heating and small space heaters |
| 250-gallon | About 200 | Mid-size demand, including whole-house heat in smaller homes |
| 500-gallon | About 400 | Whole-house heating plus other appliances in most homes |
| 1,000-gallon | About 800 | Larger homes, multiple buildings and heavy use |
See our propane tank size guide for dimensions and siting details for each tank.
How much propane does a furnace use?
The furnace is usually the biggest propane user in the house. Here is the math for a 100,000 Btu per hour furnace:
- Full burn: 100,000 Btu ÷ 91,452 Btu per gallon = about 1.1 gallons per hour.
- A cold day: if the furnace runs a total of 8 hours, it burns about 8.7 gallons.
- A 500-gallon tank: about 400 usable gallons ÷ 8.7 gallons per day = roughly 46 days of that kind of weather.
That example uses round numbers to show the method, not to predict your bill. Your actual usage depends on the furnace size, thermostat setting, insulation, the age of the house and the weather. During a cold snap, run time can climb fast, and a tank that lasted two months in the fall can drain in a few weeks in January.
What else uses propane in your home
Every propane appliance draws from the same tank. Check the data plate on each one, then add them up. Common examples include:
- Water heater. Runs year round, so it adds steady usage even in summer.
- Range and oven. Usually a small share of total use.
- Clothes dryer. Moderate use, depending on how much laundry the household does.
- Fireplace or space heater. Can use a lot if it runs for hours each evening.
- Standby generator. Uses nothing until the power goes out, then can use propane quickly. Size your tank so it can cover an outage in the middle of winter.
How to make your propane last longer
- Service your furnace or boiler every year. A clean, tuned system burns less fuel for the same heat.
- Lower the thermostat at night and when you are away. Every degree saves fuel over a heating season.
- Seal drafts and add insulation. Attics, doors and windows are the usual culprits in older homes.
- Turn down the water heater. Most households do not need water hotter than about 120°F.
- Right-size your tank. A tank that is too small means more deliveries and more risk of running low during a storm.
Do not let your tank run empty
Running out of propane is more than an inconvenience. When a tank runs dry, air and moisture can get into the system, and pilot lights go out. Before the gas can be turned back on, a qualified technician typically needs to perform a leak check. Plan your next delivery when the gauge reads about 30%, and do not wait until it drops near 20%, especially if a cold front is in the forecast.
Woodford makes it easier to stay ahead:
- Automatic delivery. We track your usage and schedule refills so you do not have to watch the gauge.
- Free tank monitoring. Residential customers can get a free tank monitor and the Anova Connect mobile app (with a minimum annual commitment). The app shows your current tank level, average daily usage and fill history, and sends alerts when your tank gets low.
- 24/7 emergency service. Our local staff are here when you need them.
Before winter sets in, walk through our propane tank safety checklist to make sure your tank and lines are ready for snow and ice.
Frequently asked questions
Does propane go bad?
No. Propane does not degrade over time, so propane stored in a properly maintained tank stays usable indefinitely. The tank itself, valves and regulator still need periodic inspection.
How long does a 500-gallon propane tank last?
A 500-gallon tank holds about 400 usable gallons. Heating a typical home in a cold month, that might last several weeks. Running only a water heater and range, it can last many months. Use the Btu math above with your own appliances for a better estimate.
How long does 100 gallons of propane last?
At full burn, a 100,000 Btu furnace uses about 1.1 gallons an hour, so 100 gallons covers roughly 90 hours of furnace run time. Smaller appliances, like a 40,000 Btu water heater, use about 0.44 gallons an hour while burning.
When should I order more propane?
Order when your gauge reads about 30%. In winter, call earlier if a cold snap or storm is coming, since delivery demand rises and roads can close.
Never run low with Woodford Propane
Woodford delivers propane to homes, farms and businesses from 10 regional bulk plants in central West Virginia and the Tri-State area of northern West Virginia, southern Pennsylvania and western Maryland, with zero hidden fees. Comparing fuels? Read heating oil vs. propane. Request a propane quote, open an account, learn about residential propane service, or call us at 1-800-927-3688.
