Short answer: The 30-year fixed averaged 6.65% for the week ending August 20, 2026, per Freddie Mac. At that rate, every $100,000 you borrow costs $641.96 a month in principal and interest, excluding taxes and insurance. On the East Bay single-family median of $1,235,000 with 20% down, that is $6,343 a month in principal and interest alone.
Start with one number you can carry in your head
Most rate coverage is written to make you feel something. This post is written so you can do the arithmetic yourself.
A fixed-rate payment is a fixed multiple of the amount borrowed. At 6.65% over 30 years, that multiple is $641.96 per month for every $100,000 of loan. Nothing about the house changes it. A $500,000 loan is five times that, $3,209.80. A $1,000,000 loan is ten times it, $6,419.60.
The mechanics: the monthly rate is 6.65% divided by 12, or 0.554167%, which over 360 payments produces a payment factor of about 0.0064196 of the loan per month.
Every payment figure in this post is principal and interest only. It excludes property taxes, homeowners and fire insurance, HOA dues and mortgage insurance. In the East Bay those additions are not rounding errors, and I come back to them at the end.
The same math at East Bay price points
Here is that factor applied to real medians. City figures are Redfin, three months ending June 2026; the East Bay single-family row is RE/MAX Accord, May 2026. All rows assume 20% down at 6.65%.
Market and median price | 20% down payment | Loan amount | Monthly principal and interest |
|---|---|---|---|
Richmond, $649,646 | $129,929 | $519,717 | $3,336 |
San Leandro, $888,017 | $177,603 | $710,414 | $4,561 |
Oakland, $898,511 | $179,702 | $718,809 | $4,614 |
El Cerrito, $1,179,358 | $235,872 | $943,486 | $6,057 |
Alameda, $1,184,855 | $236,971 | $947,884 | $6,085 |
East Bay single-family median, $1,235,000 | $247,000 | $988,000 | $6,343 |
Berkeley, $1,509,179 | $301,836 | $1,207,343 | $7,751 |
Work one row by hand. Oakland: $898,511 times 0.20 is a down payment of $179,702, leaving a loan of $718,809, or 7.188 units of $100,000. Multiply by $641.96 and you get $4,614 a month in principal and interest.
The spread is the real story. Richmond to Berkeley is $4,415 a month for what is often a comparable number of bedrooms: the price of the school district and the block, expressed monthly.
Down payment moves the number more than people expect. At the Oakland median, 10% down instead of 20% raises the loan to $808,660 and the payment to $5,191, a difference of $577 a month, before any mortgage insurance a lender may require. Have a lender price both scenarios including that insurance, whose cost varies by credit profile and program.
The $1.25 million line, and why it sits where it does
Alameda and Contra Costa counties share a conforming loan limit of about $1.25 million for a one-unit property in 2026, and FHA and VA limits match it. Confirm the exact figure with your lender, because it resets annually.
At the limit, a conforming loan carries about $8,020 a month in principal and interest at 6.65%, and with 20% down it corresponds to a purchase price near $1.56 million. Above that, you are shopping jumbo: different underwriting, different reserves, sometimes a different rate. Berkeley's median of $1,509,179 sits just under the line. More in jumbo vs. conforming in the East Bay.
Working backward from a payment you are comfortable with
Most buyers start with a monthly number they can live with, and you can invert the same factor. Divide your target payment by $641.96 and multiply by $100,000. That is your loan. Divide by 0.8 for the purchase price at 20% down.
Target monthly principal and interest | Loan amount at 6.65%, 30 years | Purchase price with 20% down |
|---|---|---|
$5,000 | $778,859 | $973,574 |
$6,000 | $934,631 | $1,168,288 |
$7,000 | $1,090,402 | $1,363,003 |
$8,000 | $1,246,174 | $1,557,718 |
Again, principal and interest only. Add taxes and insurance on top of every row before you compare it to your budget.
The 15-year comparison nobody runs
The 15-year fixed averaged 5.95% the same week. On a $988,000 loan, the 30-year at 6.65% costs $6,343 a month and the 15-year at 5.95% costs $8,311. That is $1,968 more, which is where most buyers stop.
Here is what stopping there costs. Over the full term the 30-year pays about $1,295,000 in interest; the 15-year pays about $508,000. The gap is roughly $787,000 on the same $988,000 borrowed. That is not an argument that everyone should take a 15-year loan. It is an argument that the comparison deserves five minutes rather than zero.
What the payment leaves out
Principal and interest is the part I can calculate exactly. Here is the part I cannot.
- Property taxes reset when you buy. Under Proposition 13 your assessed value becomes market value on the purchase date, at a 1% base rate plus voter-approved bonded indebtedness, with future increases capped at the lower of California CPI or 2%. The seller's bill tells you nothing about yours. Contra Costa effective rates typically run roughly 1.10% to 1.40% of assessed value for 2025-26, higher in Mello-Roos areas. I have no verified Alameda County rate, so have your lender pull the parcel's figure.
- Insurance is a live variable in the hills. Availability, not just price, can decide whether a deal closes. Quote the specific address during your contingency period.
- Payment dates. The first tax installment is due November 1 and delinquent after December 10; the second is due February 1 and delinquent after April 10, each carrying a 10% penalty.
One last thing rate math cannot capture. In the three months ending June 2026, per Redfin, 68.5% of Oakland homes and 83.1% of Berkeley homes sold above list. A pre-approval sized to the list price is not sized to this market; I explain the convention in why East Bay homes sell 30% over asking and the current picture in the East Bay housing market update.
Frequently asked questions
What is the monthly payment on a $1 million mortgage at 6.65%?
About $6,420 a month in principal and interest on a 30-year fixed at 6.65%, excluding property taxes, insurance and any HOA dues. The underlying figure is $641.96 per month for every $100,000 borrowed, so a $1,000,000 loan is ten times that. Rates change weekly, and the 6.65% average comes from Freddie Mac for the week ending August 20, 2026.
How much do I need to earn to buy a median-priced East Bay home?
I will not publish an income figure, because qualification depends on your debts, credit, down payment, loan program and the property's taxes and insurance. What I can give you is the payment: $6,343 a month in principal and interest on the $1,235,000 East Bay single-family median with 20% down at 6.65%. A lender turns that into your qualifying number.
Is a 15-year mortgage worth it at 5.95%?
It depends on cash flow tolerance. On a $988,000 loan, the 15-year at 5.95% costs about $8,311 a month in principal and interest versus $6,343 on the 30-year at 6.65%. Over the full terms, total interest is roughly $508,000 versus $1,295,000. The savings are large and so is the monthly commitment. Run both with your lender.
What is the conforming loan limit in Alameda and Contra Costa counties?
Both counties share a one-unit conforming limit of about $1.25 million for 2026, since they sit in the same metropolitan area, and FHA and VA limits match it. At that loan size, principal and interest runs about $8,020 a month at 6.65%. With 20% down, the limit corresponds to a purchase price near $1.56 million. Confirm the current exact figure with your lender.
Sources
- Freddie Mac PMMS, week ending August 20, 2026: 30-year fixed 6.65%, 15-year 5.95% — link
- Redfin, medians and share sold above list, three months ending June 2026 — link
- RE/MAX Accord, East Bay single-family median, May 2026
- Conforming loan limits, 2026, Alameda and Contra Costa — link
- California State Board of Equalization, Proposition 13 — link
Mark Lederer leads The Lederer Team at Red Oak Realty, with 25 years and more than 1,000 closed East Bay transactions. He coordinates with lenders, insurance brokers and financial planners on every purchase and accepts no referral fee from any of them, so the introduction is based on who handles your file well. To run these numbers against a specific address and a real pre-approval, call 510-774-4231, email [email protected], or set up a consultation.
