Looking to retire rich? It turns out who your employer is can make a big difference.

The fascinating results
Bloomberg recently revealed its employees poured through the benefits data at the 250 largest companies in America over the last six months to determine which ones provide the best retirement benefits to employees.

Bloomberg explored the percentages each company matches for a given employee's contribution to a 401(k) plan, what the company provides regardless of what the employee puts in, how long an employee has to stick with the company to receive the benefits, and more.

This matters because now, more than ever, Americans are dependent on things like 401(k) plans to retire. Since 1995, the balance of 401(k) plans has grown by nearly 400%, from $864 million to $4.2 trillion, far outpacing the growth of pension plans offered by companies:

Source: Investment Company Institute.

As you can see, 401(k) plans officially overtook pension funds 10 years ago, and they haven't looked back since.

And it turns out the report shows there are big winners, and big losers, when it comes to specific companies and what they give to their employees.

Winners and losers
For example, Chesapeake Energy matches dollar for dollar up to 15% of an employee's pay based on how much the employee contributed. So let's say someone made $60,000 a year and saved $9,000 (or 15% of their salary) into their 401(k). As a result, Chesapeake would put another $9,000 into their retirement account. Not a bad pay raise! 

On the other hand, Bloomberg revealed Philip Morris International (NYSE: PM) -- which came in second place -- automatically puts 15% of an employee's salary into their 401(k) plan regardless of how much they contributed. So even if an employee didn't save a penny of their own salary, using the example above, they'd still end up with $9,000.

But on the flip side of things, it wasn't until this year -- though the ranking is based on data from 2012 -- that Facebook provided any match whatsoever. As a result, the company fell into the bottom five.

And as you can see below, there are three companies which provide the best benefits to their employees in order to save for retirement.

3. Amgen

Potential Match: 5%

Additional Contribution: 5%

Although it may not be a household name, California-based Amgen (NASDAQ: AMGN) is one of the largest biotechnology companies in the world. On its website it notes it offers "a competitive retirement benefits program," to allow its employees to "prepare for a financially secure future." 

However, troublingly, while it may offer great benefits, just this week it announced it would be laying of 12% to 15% of its workforce in an effort to restructure its business.

2. Philip Morris International

Potential Match: 5%

Additional Contribution: 15%

Next on the list is the previously mentioned Philip Morris International which provides an astonishing 15% of an employee's salary automatically into their 401(k). In addition, the company matches the employee's contribution dollar-for-dollar up to 5% of the employee's salary. This means an individual who saves just 5% of their salary would end up with 25% in their 401(k) thanks to the company's generous offerings.

1. ConocoPhillips

Potential Match: 9%

Additional Contribution: 6-9%

Topping the list is ConocoPhillips (NYSE: COP) which will match 100% of an employee's contribution up to 9% of an employee's salary -- Bloomberg attributed half of the overall scores to this factor because, "financial experts say [it] is the biggest factor in determining the size of an employee's nest egg" -- and contributed between another 6% and 9% based on the age of the employee and how long they've worked with the energy company. 

"Our goal is to help employees replace at least 80 percent of their incomes in retirement, by providing two-thirds of the savings contributions they'll need, while they save one-third," noted a ConocoPhillips benefits manager, Lynn Tramel, when contacted by Bloomberg.

The key takeaway
We must always remember that whenever we're thinking about a career change it is vitally important to consider not only the salary a company offers, but the less visible benefits -- whether 401(k) matching or others -- as well. Because while one may seem to demolish the other, a dive into the details may reveal the first glance is indeed deceiving.

Patrick Morris has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.