Total monthly cost of ownership
Cost to Own a Home in O'Fallon, Illinois
A $274,000 home here costs
$2,506per month, all in — with 20% down at today's 6.66% 30-year fixed rate.
A standard mortgage calculator would have told you $1,409. The real number is $1,098 higher every month — 78% more than the payment most buyers budget for.
Where every dollar goes
Only the first line is a mortgage payment. Change any assumption above and every figure below recalculates.
O'Fallon against St. Clair County and Illinois
| Measure | O'Fallon | St. Clair County |
|---|---|---|
| Median home value | $274,100 | $168,800 |
| Median property tax | $5,759 | $3,533 |
| Effective tax rate | 2.101% | 2.093% |
| Median gross rent | $1,312 | $1,032 |
| Population | 32,139 | 254,777 |
The weather behind that power bill
O'Fallon sits in St. Clair County, which averages a high of 90.2°F in its hottest month and a low of 24.3°F in its coldest, with 43.36" of precipitation a year and 34% of it in a single three-month stretch. That climate drives 1,579 cooling and 4,209 heating degree days, which is what sets the $214 electricity line above.
See the full climate breakdown for St. Clair County — month by month temperatures, rainy season timing, snowfall and heating and cooling costs.
Other cities in St. Clair County
Full St. Clair County cost breakdown · Every county in Illinois
Common questions
How much does it cost to own a home in O'Fallon?
A $274,000 home in O'Fallon, Illinois costs approximately $2,506 per month with 20% down at 6.66%. That is $1,409 principal and interest, $480 property tax, $107 homeowners insurance, $282 utilities and $228 set aside for maintenance.
What is the property tax rate in O'Fallon?
O'Fallon has an effective property tax rate of 2.101%, based on a median home value of $274,100 and median real estate taxes of $5,759. That is in line with the St. Clair County average of 2.093%.
What is the average home price in O'Fallon?
The median owner-occupied home value in O'Fallon, Illinois is $274,100, against $168,800 across St. Clair County.
Is it cheaper to rent or buy in O'Fallon?
Median gross rent in O'Fallon is $1,312 a month, against $2,506 to own the median home all in. Renting costs less month to month here, though renting builds no equity.
Sources & methodology
- Median home value, real estate taxes, gross rent and population for O'Fallon — US Census Bureau, American Community Survey ACS 2023 5-Year, place-level tables.
- Homeowners insurance — NAIC average premium for Illinois.
- Electricity price — EIA Electric Power Monthly Table 5.6.A.
- Mortgage rate — Freddie Mac PMMS, refreshed weekly.
- Maintenance (1%/yr) and water and sewer ($68/mo) are national estimates. Every assumption above is editable.