Understanding K-Factor and Heated Degree Days

Have you Ever wondered how propane companies calculate your usage when you are on an automatic/keepfill delivery?

Here’s how we do it. 

Let’s start with Heated Degree Days (HDD). HDD is calculated by simply averaging the high and the low temperature for the day in your market area and subtracting that number from 65. Why 65? Because it has been determined that a user of heat has the tendency to turn their heat off or would use no heat when the average temperature for the day is 65 and above.


  • Low for today is 20 degrees
  • High for today is 30 degrees
  • Average = 25 degrees
  • HDD = 40 Heating Degree Days (65-25)

The K-Factor is simply how many degree days it takes for your customer to burn ONE gallon of fuel. So if I have a 500 gallon propane tank at my customers house and they have a 6.5 K-Factor, they are going to burn one gallon of propane for every 6.5 degree days. That being said, in the above example we have 40 degree day, that means a customer that has a K-Factor of 6.5 theoretically burned 6.15 gallons of fuel that day. 

We utilize this formula to schedule out our routes to make sure the customer receives their next fill before they fall below 10%. That being said, the formula has its flaws. Changes in propane uses, like additional appliances running off of propane or additional people living in the household will throw the formula off. This is why we recommend our customers enroll in our Stable Monitored Program. That way, no matter what changes take place in the household, we have a live feed of their current consumption and tank level. With our program, we back our no run-out guarantee with a $250 credit to the account should they run out. 

The thing is, our monitored delivery program is the most reliable way to receive propane deliveries. 

Gain greater peace of mind with small, monthly payments and guaranteed fuel from our backyard to yours. At Superior Fuel, we work hard to be the future of propane technology.

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