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)
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.
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.
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.
PG&E has been “estimating” my usage because of a battery module replacement needed in my meter, and says it will all be accurately worked out once they fix it… last month they’re estimating my 1525sf home in California (avg Dec/Jan highs in the 50’s, lows in the high 30’s) – with brand new windows and a smart thermostat set to 60-65 except for 2-3 hours in the evening 68 degrees, no gas appliance use, and minimal hot water use – used 175 therms for a bill total just under $500. How far off do we think their algorithm is??
Hi Katie, wow. This truly is a horror story.
That is Crazy on the number of therms ( PGE prices are around $2.68 for first 35 therms and the rest is $3.06 per therm as of Jan 1, 2023 but will go down in March- they say) But Regardless- Something is WRONG- I have a 1997 house in Folsom and I keep my heat at 76 during the day ( yes I wish I was in Hawaii) and my total usage for the Dec 22-Jan23 of 33 days was “only” 115 Therms and I have a gas stove, oven, water heater and I love to cook and bake and sit in my walk in tub!. Call them out!
recent Dec 23, 22 to Jan 24, 23 1050 sq ft 1 story 70 yr old house with 7-8 single pane windows natural gas bill from local utility(not PGE) uses 147 therms bill $696 honest this is a record with January rate increase to $4.738/therm house set to 70 degrees F
150-200 therms is normal for my house between November and March in Northwest Indiana. The house is not old. It is 1995 and well maintained with a newer roof. We have forced gas 80% efficiency furnace and a gas hot water heater and our stove/oven is natural gas as well. This year we are paying $1.22 per therm for natural gas plus a delivery fee and electricity. Last month we had 208 therms of natural gas plus electricity for a bill of $531. That’s our biggest bill ever. Now we are suffering with a colder home trying to reduce the cost. My home is a two story 1785 sq feet with a finished basement of 700 sq ft. We have it baffled to even out heat but still crazy expensive
We had our HVAC replaced back in Dec. and since that time our gas bill has tripled and the system doesn’t run anymore than the old one did. We keep our house at 68, we have a nest thermostat and the company who installed it has been out 3 times to take readings and check for gas leaks. We went from using an average of 18 therms this time last year to our highest therm usage ever which was 47. Last three months since the furnace was installed was 37, 45 and 47 therms. We live in Az. and the coldest temps we had this year in the morning was 32. My system run time is low in my eyes. Based on what I have been tracking from 16 March to now our system has run 4 hr. 30 min. I’m at 26 therms right now. We have a hot water heater and gas stove and range. No leaks there either, already had them checked. Getting very frustrated because we upgraded our 20 year old system in fear of it failing during the summer at some point. Now wishing we would have just stuck with it. Installation company is at wits end or maybe doesn’t have someone experienced enough. They did adjust the first stage and second stage even though he said it was within the manufactures level. Frustrated. Thank you for any advice. Home is 2150 sq. ft. built in 2001. New system installed is a Trane XV80.
Hi Anthony, this truly is a mystery. The new HVAC system should, for all intents and purposes, have a higher efficiency, and specs-wise, it has. The heating load didn’t change. There is no clear rationale why you are burning 3 times the therms with the new unit. The leak might explain that, but you don’t have a leak. This is also not explained by rising gas rates. To be honest, there really is no clear explanation for why this is happening; very frustrating. If you fix this, please share what was wrong. I can’t imagine many people experiencing this, but for those who do, your info will be helpful.
Hi- I live in San Mateo California, in an 1100 sq ft duplex built in the 50’s. Home is on a crawl space with original hardwood floors (gets chilly), half the windows are new double pane, half are single old metal framed. Our PGE “allowance” is 30 therms, supposedly we are using around 50-60 therms per month… our oven/range, water heater, and forced heat are all gas. There are only two of us and we aren’t home much. Our thermostat never moves from 63. To me, this seems absurdly high usage if the average 2k sq ft home uses the same if not less. Am I trippin?
Hi there, for the low usage you practice, the 50-60 therms per month is unusually high. You could blame this on bad insulation (homes built in the 50s usually have relatively low R values) but that wouldn’t spike the usage to 2 therms per day (60 therms per month). When you see an unusually high gas usage, the first thing you should think about is a gas leak. It’s really hard to explain where all this gas goes otherwise.