How Many Therms Of Gas Per Month Is Normal? (1000-3000+ Sq Ft Homes)

December 2022 was brutal. The temperatures fell even below 0°F in places like New York and Chicago. That’s why people on forums started exchanging how many therms of gas per month they used. Needless to say, record high 200+ therms per month for 2000 sq ft 1960s houses were unusually common. That’s why we looked at how many therms of gas per month is normal.

Here are some transcripts of these monthly gas usage “horror” stories from the forums:

“Marylander with 2000+ sq ft 1930 house with old windows; 243 therms per month costing $346.” (Source: Reddit.com)

“120 therms in the last 30 days. That’s 4 therms of gas per day.” (Source: DIY Forums)

“Massachusets, 1800 sq ft house; 190 therms per month costing $332.” (Source: Reddit.com)

during winter we use more therms of gas than in the summer
During colder months (Oct-Mar), we use quite a lot of gas. That’s because heating accounts for about 70% of our yearly gas bill.

Alright, it is important that we put these numbers into the right context. These are usually monthly therm uses for the coldest month in the year (December, January). How many therms per month a household normally uses?

Obviously, this will depend on a number of factors, including home size, location, insulation or year of built (a 1990s house, for example, has better insulation than a 1960s house, on average), number of occupants, the temperature we set, outdoor temperatures, and so on.

gas consumption depends on how high you set the thermostat
Gas consumption (in therms) will obviously increase if you set the thermostat higher.

The key challenge is how to adequately make an estimation of how many therms of gas per month is normal for your house.

Apart from the forums, there is a very limited number of data sources for household monthly natural gas usage in the US. Fortunately, the US Energy Information Administration has released this 2022 Residential Energy Consumption Survey Data; you will find a total of 89 PDF and accompanying Excel sheets with data about energy usage across the US.

Sieving through this data is quite a tedious job. If done correctly, we will be able to estimate the average therms of gas per month usage. We have performed this tedious data analysis to help get you the right numbers.

Example: The results summarized in the chart below show that we use 1 therm of gas per 3-5 square feet of an average home during 6 colder months (Oct-Mar).

We will start by calculating an example for a 2000 sq ft house (to illustrate how to calculate how many therms of gas per month is normal with statistical analysis). Don’t be taken aback by how complex this calculation looks like. You will find a summary of monthly therms usage during 6 colder months (Oct, Nov, Dec, Jan, Feb, Mar) for below 1,000 sq ft house to 3,000+ sq ft house in a chart further on.

Example of results summarized in the chart: During 6 colder months, an average 1,500 sq ft to 1,999 sq ft homes uses about 45 therms of gas. 36.5 therms for space heating, 7.1 therms for water heating, and the rest for appliances, cooking, and so on.

Note: If you have a high therms per month story to share, or would like for us to calculate normal therm usage for your home, you can use the comment section below, and we’ll try to help you out.

Here is what the 2020 RECS data says about average therms of gas per month usage:

Calculating Average Therms Of Gas Per Month (2000 Sq Ft House Example)

In these databases, EIA categories energy usage for appliances, electronics, lighting, space heating, air conditioning, water heating, and so on. This data is segmented by housing type (single family home, apartments, mobile homes), ownership status, year of construction, number of household members (1, 2, 3, 4, 5 or more family members), household income (from less than $5,000 to $150,000+), and climate region (very cold/cold mixed-humid, mixed-dry or hot dry, hot humid, marine). Sadly, there is no data for square footage; ie. how many therms of gas does a 1000 sq ft or 2000 sq ft house use.

However, if we look at this 2015 data (we will be using this data set), we see a listing for average gas usage by square footage.

Example from this data: There are 14.1 million US houses ranging from 2000 sq ft to 2499 sq ft. Combined, they used 584 billion cubic feet of natural gas per year. 410 billion cubic feet of gas is used for space heating (70%), 136 billion for water heating (23%), and the remaining 38 billion cubic feet of natural gas for other uses such as cooking, appliances, and so on.

We are interested in how many therms of gas we normally use. That’s why we have to cover billions of cubic feet of gas to terms. From the EIA fuel heat content measurements, we know that 1000 cubic feet of gas is equal to 10.37 therms. That means that a billion cubic feet of gas is equal to 10,370,000 therms.

you need 100 cubic feet of gas for 1 therm of heat
How much is 1 therm of gas? 1 therm is equal to about 100 cubic feet of gas (this is a rule of thumb, accurate to 3.7%).

From 584 billion cubic feet of gas, we thus get 6,056,000,000 therms. If we divide this by 14.1 million households, we can see that an average 2000 sq ft to 2499 sq ft house uses 430 therms per year.

That would mean that the average gas usage is 36 therms per month for all months (from January to December).

Additionally, we have to note that space heating (70% or 301 therms) is used mostly in the 6 colder months (Oct, Nov, Dec, Jan, Feb, Mar). If we use the same amount of gas only during these months, that comes to about 50 therms per colder month. If we add the remaining 11 therms per month for water heating, cooking, and so on (should be roughly the same for all 12 months), we come to this estimate:

A 2000 sq ft to 2499 sq ft house will normally use 61 therms of gas in colder months.

We can write all these complex calculations in a formula that looks like this:

Average Therm Usage Per Cold Month = (Yearly Billion Cubic Feet Gas Usage / Number Of Houses) × 10,370,000 Therms × (0.3/12 + 0.7/6)

This equation is quite complex. In order to help you out calculate the average therm per month usage, we have created a chart with monthly (for cold months) therms usage for different house sizes (from below 1,000 square feet to over 3,000 square feet homes). Here is the chart:

Note: During very cold weather, the space heating can burn through a lot of therms. This will spike the gas usage way above what it’s normal; from 61 therms per month to way over 100 therms per month for a 2,000 sq ft home.

Monthly Household Gas Usage Chart (For Colder Months; US Average)

Home Size: Therms Per Cold Months (Oct-Mar): Therms For Heating: Therms For Water Heating: Therms Per Year:
Below 1,000 Sq Ft 19.7 Therms Per Cold Month 13.1 Therms Per Month 5.5 Therms Per Month 157.5 Therms Per Year
1,000 – 1,499 Sq Ft 30.2 Therms Per Cold Month 22.5 Therms Per Month 6.1 Therms Per Month 227.7 Therms Per Year
1,500 – 1,999 Sq Ft 45.7 Therms Per Cold Month 36.5 Therms Per Month 7.1 Therms Per Month 329.5 Therms Per Year
2,000 – 2,499 Sq Ft 60.9 Therms Per Cold Month 50.3 Therms Per Month 8.3 Therms Per Month 429.5 Therms Per Year
2,500 – 2,999 Sq Ft 74.8 Therms Per Cold Month 63.5 Therms Per Month 9.3 Therms Per Month 516.6 Therms Per Year
More Than 3,000 Sq Ft 84.8 Therms Per Cold Month 71.8 Therms Per Month 10.1 Therms Per Month 587.2 Therms Per Year

As you can see, in the winter (colder months), you would normally use:

  • Around 20 therms of gas for below 1,000 sq ft homes.
  • Around 30 therms of gas for 1,000 sq ft to 1,499 sq ft homes.
  • Around 45 therms of gas for 1,500 sq ft to 1,999 sq ft homes.
  • Around 60 therms of gas for 2,000 sq ft to 2,499 sq ft homes.
  • Around 75 therms of gas for 2,500 sq ft to 2,999 sq ft homes.
  • Around 85 therms of gas for more than 3,000 sq ft homes.

It is important to note that these therms per month are the average for US households. A home in Chicago or New York will obviously burn through a lot more gas than a same-size home in Texas, Florida, or California. That’s why seeing 100+ therms per month for a 2,000 sq ft home in New York is not all that extraordinary.

The household reported numbers we can see on forums, however – with 200 therms per month and more – are quite extraordinary.

The case we had at the start – “Marylander with 2000+ sq ft 1930 house with old windows; 243 therms per month costing $346.” – is way above average. Part of the reason is the very low temperatures in December 2022 that hit Baltimore. The main reason, however, is most probably suboptimal insulation (1930 house, old windows).

We hope that you can use this statistical analysis of how many therms per month is normal in the winter to get an idea if your gas usage is in line with what is expected. If you have a specific case, or a story about how many therms you burned during a cold month, you are welcome to share it in the comments below. We can help you do some of these calculations to see how many therms per month you should normally be using.

Thank you.

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