Your new paycheck may feel like chump change. (iStock)

Job hunters typically know to research pay levels and to look into how their cost of living may change before they accept a new job. But some people may focus so much on their salary that they forget to calculate how much more they might end up paying in rent, on their commute or on other expenses they weren’t anticipating when they took the job.

The end result can mean starting an exciting new job with a smaller-than-expected paycheck.

“Often times when people move, they have no idea what the overall cost is,” says Kristen Robinson, senior vice president of Fidelity Investments’ Women & Young Investors unit.  “They’re just looking at the salary increase and thinking ‘wow I’m making 10,000 more a year.’”

Instead, some people may forget that changing jobs can also mean having to pay more for certain benefits or losing some perks altogether. Their health-care costs may go up. Their 401(k) match may go down. And by changing jobs they might be leaving behind some other cash, such as an unclaimed bonus.

After they take all of those changes into consideration, their new paychecks may not feel so big, Robinson said.

Indeed, close to 70 percent of job hunters said salary was their top priority when weighing a job offer, according to an online survey released in January by Glassdoor, a job listing website. Next up was location and commute, cited by 59 percent of job hunters. Benefits and perks came in third, mentioned by 57 percent of people surveyed.

Of course, certain parts of an offer, such as the 401(k) match or the cost of a health-care premium, are not necessarily negotiable. But knowing that you’ll have to spend more on those benefits may encourage you to negotiate for a bigger paycheck. Or at the very least, you can use the information to look at the big picture before you take the job, says Robinson.

Fidelity released a tool this week that helps people compare how much their finances would change if they took the job offer. In addition to comparing paychecks and bonuses for the current job and the job offer, the tool factors in 401(k) matches, cost of living changes and other costs. It reminds people to think about the retirement money they might lose because they haven’t worked at the company long enough to become keep the company match.

Job seekers should crunch the numbers on the perks that are most important to them, says Scott Dobroski, a spokesmen for Glassdoor. For someone with a family or a chronic health condition, it may be helpful to estimate how their health costs may change if they took the new job. For others, it may be more important to ask for perks that may have a less obvious effect on their wallets, such as a flexible work schedule, he says.

The point is to do the research and ask, he says. “If you do not ask, you will not receive,” Dobroski says.

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