For heating, we use a variety of residential propane tank sizes. The 100 gallon propane tank is the smallest of these tanks. We’re going to see how long a 100-gallon propane tank will last **home heating**,

The math here seems simple at first. For example, if we use 2 gallons of propane per day for heating, a 100-gallon propane tank will last a long time. ~~50~~ 40 days. that’s because *80% tank rule*, a 100 gallon when full is not 100 gallons of propane; Contains **80 gallons of propane** (safety measures).

However, in practice, we need to pay attention to our heating needs. These mainly depend on **size of our house** *(square footage)*, As we’ll see next, if we take the average American household size and propane consumption, a 100-gallon propane will be **from anywhere in the past 11 days to 85 days** (about 3 months).

To calculate how long a 100-gallon propane lasts, we need to be aware of the following metrics:

- 1 gallon of propane contains 91,500 BTU of heat energy.
- A 100-gallon propane tank (when 100% full) holds 80 gallons of propane. This is a security measure; If 100 gallons contained 100 gallons of propane, the pressure on the inner wall of the propane tank could be dangerously high at high temperatures.
- These 80 gallons of propane contain
**7,320,000 BTU of thermal energy**,

There are two ways we can calculate how long a 100 gallon propane tank will last:

**by heating up the demand.***Example:*Let’s say you need 10,000 BTU/hr to heat your home. This means that a 100-gallon propane tank will last 7,320,000 BTU 10,000 BTU/h = 732 hours; That’s 30.5 days or about 1 month.**According to the size of the house (500 sq ft to 4,000 sq ft homes).**Here we use the average winter propane consumption per square foot (0.34 gal/sq ft; based on average use).*Example:*To heat an average 1,000-square-foot home for 6 months (October to March), 340 gallons of propane will be needed. This means that a 100-gallon tank will last about 42 days.

We’ll show you how to do both calculations. If you know your heating demand (from 10,000 Btu/h to 200,000 Btu/h), you should follow the first calculation.

*Easy* How to get an idea of how long a 100-gallon tank will last **see second count**Based on average propane consumption and size of the household.

*pay attention:* You can check here how long all propane tanks (from 1 lb to 2,000 gallons) last.

Let’s start with the first theoretical calculation, and we’ll follow up with the second calculation (depending on the size of the house) which is much more practical:

## First Count: How Long a 100-Gallon Propane Tank Will Last (Based on Heating Needs)

It is quite simple in theory. We only need two figures to calculate how long a 100-gallon tank should last. these:

- A 100-gallon propane tank holds 7,320,000 BTU of heat energy. this is
**easy share**, - What is your average heating requirement? It could be 10,000 BTU/h, 20,000 BTU/h, 30,000 BTU/h etc. this is
**the hard part**: Evaluating your average need is not that easy.

If you figure out how many Btu/h you burn throughout the winter, you can easily calculate how long a 100 gallon tank will last.

*Example:* Let’s say we need an average of 20,000 BTU/hr to heat our house during the winter months. We know that a full 100-gallon propane tank contains 7,320,000 BTUs. Assuming 100% efficiency (in fact, the efficiency of burning propane is about 98%), we can calculate how many hours/day a 100-gallon will last like this:

**Lasts for a 100-gallon tank** = 7,320,000 BTU = 20,000 BTU/h *366 hours*

That is, about 15 days or half a month.

Here’s a calculated table of how long a 100-gallon propane will last if we know the heating requirement (Btu/h):

Heating Requirement (Btu/h): |
Lives for a 100-gallon tank: |

5,000 Btu/h | 61 days |

10,000 Btu/h | 31 days |

20,000 BTU/h | 15 days |

30,000 Btu/h | Ten days |

40,000 Btu/h | 8 days |

50,000 BTU/h | 6 days |

In many cases, this first calculation is theoretically correct but very impractical. This is because it is almost impossible to determine exactly how many Btu/h we need (on average) during a heating period of 6 months.

When determining how long a 100-gallon propane tank should last, we use a second calculation (based on the size of the house):

## Second Count: How Long a 100-Gallon Propane Tank Will Last (Depending on the Size of the House)

Since it is very difficult to adequately assess heating needs in Btu/h, it is easy if we use the average propane consumption.

As we wrote in our article on how long a propane tank lasts, we can take two statistical measurements to determine average house propane consumption:

- An average American household consumes approximately
**750 gallons**of propane per heating season. - The average American household size is
**2,200 square feet**,

Based on this, we can calculate that we need an average of 0.34 gallons of propane per square foot per heating season. Here is the calculation:

750 Gallon Propane = 2,200 Square Foot House **0.34 gallons propane per square foot**

This is a very useful assessment. Now we can estimate how long a 100 gallon tank will last for 500 sq ft, 1,000 sq ft, 2,000 sq ft homes, etc.

You’ll find a calculated table for the most common house sizes below. First, let’s turn to an example to illustrate how you can use this approximation.

*Example:* Let’s say we have a house of 1,500 square feet. We know that on average we will need 0.34 gallons of propane to heat 1 square foot in the summer season. How much propane do we need to heat for a full 6 months?

**need for hot weather** = 1,500 square feet × 0.34 gallons/square foot = **510 gallons of propane**

This means that an average 1,500-square-foot home will burn 510 gallons of propane over a 6-month-long heating season (180 days).

We know that a 100 gallon tank contains 80 gallons of propane. It won’t last the entire heating season but it will keep the heat on for some time. Exactly how long? Here’s how we calculate it:

**Lasts for a 100-gallon tank** = (80 gallons 510 gallons) × 180 days = **28 days**

This means that a 100 gallon tank will last about a month if we use it to heat an average 1,500 square foot home.

What about smaller 500, 1,000 square foot homes, or larger 2,000, 3,000, 4,000 square foot homes?

Here’s a calculated table of how long a 100-gallon tank will last for all of these home sizes:

House Size (Sq. Feet): |
Lives for a 100-gallon tank: |

500 square feet | 85 days |

1,000 square feet | 42 days |

1,500 square feet | 28 days |

2,000 square feet | 21 days |

2,500 square feet | 17 days |

3,000 square feet | 14 days |

3,500 square feet | 12 days |

4,000 square feet | 11 days |

We hope this shows a bit about how long a 100 gallon tank will last. You can see a similar calculation for a 500-gallon propane tank here.

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