A research group that promotes affordable housing has unveiled a new way of calculating what many already know: Bay Area residents pay a high price for living where they do.

Housing and transportation costs eat up nearly 60 percent of the median income of Bay Area families, according to a report by the Urban Land Institute's Terwilliger Center for Workforce Housing. The average household spends $28,000 on housing and $13,400 on transportation each year.

"A lot of people don't realize what their monthly transportation costs are," said Linda Young of the Center for Neighborhood Technology, which did most of the research for the study.

"Usually the costs are unbundled. Unlike a mortgage payment which people can probably tell you off the top of their head, it's not something that's easily accessible to them."

The burden of paying for homes and commutes is even higher — 63 percent — for the inner East Bay communities hugging the Bay, which the study attributes more to lower incomes west of the hills than of comparatively higher housing and transportation costs.

It's highest in San Pablo — a striking 81 percent of the median income is spent on housing and transportation, with several other East Bay cities including Berkeley and Richmond following close behind.

Residents who face the most extreme housing and transportation burdens have little left over — in some counties, an average of $1,000 monthly or

The report will be released at the Urban Land Conference, a meeting that has brought more than 5,000 developers, builders, city planners and others to San Francisco this week. Two former directors of the federal Department of Housing and Urban Development — Henry Cisneros from the Clinton administration and Steve Preston from the Bush administration — are scheduled to unveil the study this morning.

One of the agendas of the conference, hosted by the 72-year-old Urban Land Institute, is to get more people and presumably more housing in high-density urban places close to transit.

Along with four days of meetings in San Francisco, organizers are taking guests on tours of transit-oriented developments in Pleasant Hill and Dublin and revitalized urban and retail areas in Oakland, Berkeley and Emeryville.

As evidence of the importance of their goals, proponents will use the study and a model they call "location efficiency," a metric that shows lower cost burdens in places such as San Francisco and Alameda counties because of the proximity of residents to job clusters and public transit.

Santa Clara County residents spent 54 percent of their incomes on homes and commutes, the lowest rate of the nine Bay Area counties, while Sonoma County was the highest, with 66 percent.

"Santa Clara is a more location-efficient place," Young said. "The residents who live there live closer to their jobs; they live closer to schools and stores."

The researchers have also created an online calculator, to be available at www.bayareaburden.org, that allows viewers to plug in their costs and compare them with local averages.

According to the report, three-fifths of all Bay Area residents live in communities that are unaffordable to households that make less than $80,000.

By the federal government's definition, housing is affordable if it costs less than 30 percent of household income.

There is no similar definition for transportation costs, but Young said some use a rate of 18 percent or lower of income as reasonable. On both counts, many Bay Area residents have costs that exceed those rates.

Much of the report is based on data from 2007, before the recession, which means changes in income, gas costs and other factors since then have not been taken into account.

"I think that land use changes and the built environment change slowly over time," Young said, "which is all the more reason we need to have good information about it now."