How Long Does a Tank of Heating Oil Last?

It is January, 2021 right now which means heating oil season is in full swing! While you are thinking about when to order heating oil, you may be wondering how long a tank of heating oil lasts. A tank of heating oil lasts as little as a few weeks, and as long as a season; see how long your heating oil will last below!

Heating Oil Tank Size

An obvious factor that will impact how long the tank lasts is the size of the tank. The most common heating oil tank size is 275 gallons. A 275 gallon heating oil tank holds approximately 250 gallons of heating oil when full. The next most common oil tank size is 330 gallons. A 330 gallon fuel oil tank has a nominal capacity of about 300 gallons.

It is also not uncommon for a home to have ‘twin tanks’ where two 275 or two 330 gallon tanks are plumbed together. This gives the homeowner more capacity and the ability to order heating oil less frequently.

Homes with in-ground tanks tend to have 550 gallon, or even 1000 or 2000 gallon tanks! In-ground oil tanks are less and less common and are often replaced with above ground tanks when the house is sold.

This 275 gallon heating oil tank holds 250 gallons of home heating oil and is the most common oil tank size. The 275 gallon oil tank shown measures 5 feet long. The second most common tank is 330 gallons. The 330 gallon tank measures 6 feet long – or one more foot than the 275 gallon tank.

House Size Impacts Heating Oil Usage

Once you’ve determined the size of your heating oil tank, you’ll need to know how much oil your home requires per day to determine how long the oil tank will last. The factors that impact how much heating oil you use are:

  • The size of your house. A 1500 square foot house may use only 500 gallons a year, whereas a 3500 square foot house may use over 1500 gallons per year.
  • The energy-efficiency of your house. A well-insulated 2500 square foot house may use as little as 600 gallons per year, whereas the same size house with poor insulation and drafty windows could use over 1200 gallons per year.
  • The age of your heating system. Well-maintained heating oil systems tend to last much longer than comparable gas systems, often lasting 30 years or longer! While this is great, technology continues to make these systems more efficient. Upgrading to a new oil-fired heating system can reduce heating oil costs by up to 30%.
  • The temperature (both inside and outside). Turning down the thermostat a few degrees is a sure way to reduce your heating oil usage. But a bigger factor is the outdoor temperature. On a 10° day, an average home may use 8-12 gallons of heating oil to keep warm. On a 30° day, the same home may only use 5-7 gallons of heating oil.

Heating Oil Used Per Day

Once you know your home size, you can use the following tables to figure out how much heating oil you will use per day. With this, you can estimate how long your oil tank will last you.

Keep in mind, however, that you do not want to let your tank go completely empty! Always order heating oil when your tank is at around 1/4 full to ensure you do not run out of heating oil.

A 2500 square foot home will use approximately 4-6 gallons a day on a 30 degree winter day.

How Long Will a Tank of Heating Oil Last

There is one more factor that you need to keep in mind to determine how long your tank of heating oil will last you: the reorder point. Just like with a car, it is important that you do not let your tank run completely empty. This will not only cause your burner to shut down, but can cause sludge to get sucked into the lines, clogging the system.

As such, it is highly recommended to order heating oil when your tank is 1/4 full. “Reorder at a quarter” is a good way to remember this.

“Reorder at a quarter” is a good rule of thumb for when to order heating oil. A heating oil tank gauge only provides an approximation of the oil tank level, so it is important to not let the tank run too low. Since a 275 gallon oil tank holds at most 250 gallons, and you should reorder at 1/4 tank (68 gallons), we can take 250-68 = 182 to determine how much heating you can use between fills. 182 gallons, at 5.2 gallons per day, will last for approximately 35 days, or just over one month.

The 1/4 mark on a 275 gallon tank is approximately 68 gallons. Since a 275 only holds 250 gallons when full, this means you have 182 gallons (250 – 68 = 182) of usable heating oil before you need to order heating oil. Look at the table above to determine your average heating oil usage based on recent temperatures, and divide this number into the total number of usable gallons. Example:

  • Home size: 2500 square feet
  • Average temperature since last fill: 30° F
  • Average gallons per day @ 30° F: 5.2 gallons per day
  • Tank size: 275 gallons (holds 250)
  • Reorder point: 1/4 tank or 68 gallons
  • Usable gallons between fills: 250-68 = 182 gallons
  • Number of Days Between Fills: 182 gallons / 5.2 gallons/day = 35 days

With an average outdoor temperature of 30° F, a 275 gallon tank in a 2500 square foot home will last approximately 35 days between fills.

When To Check Your Heating Oil Tank and Order Oil

The last thing you want is to wake up to a freezing cold house in the middle of winter because you ran out of heating oil. If you do run out of heating oil, check out our step-by-step guide here: what to do if you are out of heating oil.

With an old-fashioned float gauge in your tank, we recommend checking the level once a week, or at least once every two weeks during the winter. Set a reminder in your smart phone to go down and check the tank periodically.

Alternatively, you can install a Smart Oil Gauge on your tank, and simply check your heating oil level from your smart phone. Program text and email alerts when your tank gets low, and never worry about heating oil again.

If you are new to heating oil and are wondering how much heating oil your home may use, consider the table below for the expected usage for an average winter in CT.

This chart approximates how many gallons of heating oil a home in CT may expect to use. The energy-efficiency of your home and outside temperature will skew your results to either side of these ranges in a given winter.

Check Heating Oil Prices And Order Heating Oil Online

When your heating oil tank is down to 1/4 full, it is time to order heating oil. Check heating oil prices near me online, and go to a site like FuelSnap to quickly compare heating oil prices between local dealers. Read reviews and order oil online with a credit card. Choose exactly how many gallons of heating oil you need to avoid surprises. And finally, set a reminder to check your tank every week or two to make sure you do not run out of heating oil.

Happy heating,