A year ago: $2,442 a month on $400,000
A year ago, in late October 2025, a $400,000 mortgage cost $2,442 a month in principal and interest, at Freddie Mac's average 30-year rate of 6.17 percent [1]. Principal is the loan balance you pay down. Interest is what the lender charges you to borrow it.
The same loan now: $2,726 a month
The same $400,000 mortgage costs $2,726 a month at 7.24 percent, Freddie Mac's average as of October 29, 2026 [1]. The higher rate adds $284 a month, or about $3,400 a year, to the same debt.
The rate has come down a little. Freddie Mac's average was 7.32 percent one week earlier, so the October 29 average takes $22 a month off this loan [1].
Here is what three loan sizes cost each month in principal and interest on a 30-year fixed loan:
- $300,000 mortgage: $1,996 at 7 percent, $2,044 at 7.24 percent [1].
- $400,000 mortgage: $2,661 at 7 percent, $2,726 at 7.24 percent [1].
- $500,000 mortgage: $3,327 at 7 percent, $3,407 at 7.24 percent [1].
Median homes: $2,047 in Will County, $1,621 in Grundy County
With 20 percent down at 7.24 percent, the monthly payment on a median-priced home is $2,047 in Will County and $1,621 in Grundy County. A median is the middle sale: half the homes sold for more and half sold for less [4].
- Will County: Redfin's median sale price for the three months ending September 2026 was $375,410, up 2.9 percent from a year earlier [2]. A 20 percent down payment is $75,082. The loan is $300,328 and the payment is $2,047.
- Grundy County: Redfin's median sale price for the same three months was $297,285, down 4.1 percent from a year earlier [3]. A 20 percent down payment is $59,457. The loan is $237,828 and the payment is $1,621.
- Chicago Metro Area: These nine counties include Will and Grundy. Illinois REALTORS put the median price at $385,000 in September 2026, up 6.9 percent from a year earlier [4]. A 20 percent down payment is $77,000. The loan is $308,000 and the payment is $2,099.
At the 6.17 percent average of late October 2025, the same Will County loan would cost $1,834 a month, which is $213 less [1][2]. The same Grundy County loan would cost $1,452 a month, which is $169 less [1][3]. Redfin's median covers three months and the Illinois REALTORS median covers one, so compare each figure only with its own source.
Taxes and insurance: what the payment leaves out
Taxes and insurance come on top of every payment above. The Consumer Financial Protection Bureau says many lenders require you to pay property taxes and homeowners insurance through an escrow account [5]. Escrow is money collected with your monthly payment and used to pay those bills for you [5]. Both bills can change from year to year, and your total payment changes with them [5].
A smaller down payment can add one more cost. With less than 20 percent down on a conventional loan, you might have to buy private mortgage insurance, or PMI, which protects the lender and not you [6]. The most common way to pay for PMI is a monthly premium added to your mortgage payment [6].
Your own rate: what changes it
Your own rate can differ from Freddie Mac's average, which comes from loan applications lenders across the country send to Freddie Mac [1]. The bureau shows that credit score, down payment, loan term and loan type each change the rate a borrower is offered [8].
The step that turns these examples into your own number is comparing Loan Estimates from more than one lender. The bureau's reason is that fees, points, mortgage insurance and closing costs all add up along with the rate [8].
Mortgage points: the price of a lower rate
One mortgage point costs 1 percent of the loan, so one point on a $400,000 mortgage is $4,000, paid at closing [7]. How far the rate drops for each point depends on the lender, the kind of loan and the market, so ask each lender to show you the change [7]. The bureau says points can be a good choice if you plan to keep the loan for a long time [7].
What this means if you are buying or selling here
If you are buying in Will or Grundy County, start from the monthly number you are comfortable with, then work back to a loan size and a price. If you are selling, the buyers who tour your home are working from this same math. Redfin's report through September 2026 shows Will County homes spending a median 58 days on the market, up from 52 a year earlier [2].
