Most rent versus buy advice for Bay Area families ends with a shrug and an it depends. That is not much help when your lease renewal is sitting in your inbox and your second kid needs a bedroom. The truth is you can get to a real answer in an afternoon with five numbers, a calculator, and a little honesty about your timeline. Here is how to do it, with a worked example using current figures so you can see where each number comes from and swap in your own.
Step one is pinning down what renting actually costs you, not what it cost when you signed. San Francisco rents have climbed to the highest levels in over a decade of tracking, with the median two-bedroom now at $5,700 a month and some neighborhoods up more than 50 percent in a single year, according to reporting from the SF Standard. If your current rent is below market, use the number you would face at your next move or renewal, because that is the figure a purchase actually competes against. For this walkthrough, we will use $5,700.
Step two is pricing the home and the loan. Look at what the homes you would genuinely buy are selling for, not regional averages. Statewide, the California Association of Realtors put the median at $904,640 in June 2026, and single-family medians in San Francisco and San Mateo counties run above $2 million, but condos and homes in much of the East Bay come in well under those figures. Say your target is a $1 million two-bedroom condo with 20 percent down, leaving an $800,000 loan. Then get the current rate rather than guessing. As of July 2026, mortgage rates in California on a 30-year conventional loan were 5.875 percent, per Lower’s published figures. At that rate, the $800,000 loan carries a principal and interest payment of about $4,732 a month.
Step three is adding the ownership costs that never appear in a rent check. Property tax is the big one, and it is knowable to the decimal. The San Francisco Treasurer lists the secured rate for fiscal year 2025-26 at 1.18268325 percent of assessed value, and your assessed value resets to your purchase price when you buy. On $1 million, that is about $986 a month. Then get a real homeowners insurance quote and the actual HOA dues for the buildings you are considering rather than estimating. For the example, assume $250 a month for insurance and $600 for HOA dues, numbers you should replace with your own quotes. That brings the all-in monthly cost to roughly $6,568. At first glance, renting at $5,700 looks like the clear winner. Do not stop here.
Step four is subtracting the part of the payment that is not a cost. This is the step almost everyone skips, and it changes the answer. Lower’s national analysis of owning versus renting found that once you count principal paydown and appreciation as equity rather than expense, buying beat renting in 56 of the 136 cities studied. The Bay Area sits outside that study’s FHA-focused scope, but the method is exactly what you need here. In year one of the example loan, about $838 of each monthly payment goes to principal. That money is not gone; it is moving from your checking account into your net worth. Subtract it, and the true monthly cost of owning drops to about $5,730.
Step five is the comparison, plus a stress test. In the example, $5,730 to own against $5,700 to rent is essentially a dead heat, and that is assuming the home appreciates zero percent. Every 1 percent of annual appreciation on a $1 million home adds about $833 a month to the equity side, which would tip the math decisively toward buying. But run the pessimistic case too. In Lower’s study, 34 of the 136 cities posted falling values that erased the equity gains from payments. If the answer only works when you assume strong appreciation, that is a bet, not a plan. If it works at zero, appreciation becomes upside instead of a requirement.
One gate sits on top of all five steps: your timeline. Buying and later selling carries transaction costs on both ends, and those costs get spread across however many years you stay. If a job change, a move for schools, or a growing family is likely to push you out within about five years, the math above rarely survives, and renting wins almost regardless of what the monthly comparison says. Plan to stay longer, and the numbers get better every year, helped by the fact that your assessed value can rise no more than 2 percent annually under Proposition 13 while your rent has no such cap.
So the decision rule looks like this. If your true monthly cost of owning at zero appreciation comes in at or below your realistic rent, and you expect to stay at least five years, buy. If the ownership number is higher but close, decide how much appreciation you are willing to bet on to close the gap, and be honest that it is a bet. If your timeline is short, rent and revisit.
Two last practical notes. Before finalizing anything, check whether you qualify for CalHFA down payment and closing cost assistance or San Francisco’s own buyer programs, because for families near the edge, they can move the answer. And rerun this math whenever rates shift meaningfully, since a half-point move on an $800,000 loan changes the monthly figure by hundreds of dollars and can flip the outcome by itself.
