If you're in the market for a new job, take note: Not all company retirement plans are created equal. If you're not careful, you can easily go from a gig with a generous 401(k) program or a traditional pension to one with no retirement plan at all. 

This Bloomberg data visualization lets you plug in details of your own retirement plan to see how it ranks against plans at the largest companies in the S&P 500-stock index. The information might help you get a better retirement plan from your current employer or might be good to know if you're applying for a job at one of these big companies. 

But if you’re considering a new job elsewhere, your time to ask a potential employer about its retirement plan might be brief. To get the answers you need to make an informed decision, here are four questions that financial advisers suggest you ask about a company's retirement program, ranked in order of importance.  Is there a retirement plan at all? 

This one may seem obvious, but about half of American private-sector workers don’t have a retirement plan. Larger companies usually offer a 401(k) plan, though some still offer a defined-benefit pension. Small businesses may have simpler individual retirement accounts, such as SEP-IRAs and Simple IRAs. “Any plan is better than no plan,” says Denver-based financial planner Kristi Sullivan.How much does the company kick in?

Ask how the company matches 401(k) contributions. The highest-rated employer on the Bloomberg 401(k) ranking is ConocoPhillips. For the first 1 percent of salary that employees contribute to their 401(k), the company contributes 9 percent to the plan. It also adds an additional 6 percent to 9 percent as profit sharing.

Lavish benefits like this are rare, but even a moderately generous 401(k) can add thousands of dollars in tax-deferred compensation each year. Profit sharing is more common at small companies than at large ones, says Chris Chen of Insight Financial Strategists. Less than half of the largest companies in the S&P 500 offer that benefit.How long do I need to wait?

Sometimes employees must work a year before they’re allowed to sign up for a retirement plan. In other instances, company 401(k) contributions don’t vest right away. That means if workers leave for a new job after a couple years, they might not be able to take the company match with them.What are the fees like?

If you can get your hands on a company's official 401(k) plan document, Chen says, you should be able to get fee details. You could also ask if the plan offers index mutual funds, which are almost always the cheapest fund option. All the large companies rated by Bloomberg offer at least one such fund.

Fees are worth asking about, because they have a huge long- term effect on retirement planning, says Michael Finke, a professor of personal financial planning at Texas Tech University. Take the addition of 1 percent to your annual fee. If you pay 1.5 percent rather than 0.5 percent, “you’re going to have to save 25 percent more for retirement to have the same amount of money after a 40 year working period,” Finke says.