stock market

For every rule of thumb, there are hundreds of people who would quibble with it.

We saw that just recently with a USA Today columnist who quantified exactly how much you need to save for retirement (his answer, via an analysis by T. Rowe Price: $82.28 a day). Lots of people didn’t like that the number was an estimate, an average, and that their own mileage may vary.

But many more people don’t have the patience, knowledge or energy to sort through all the potential factors for every financial decision. Sometimes, they just want an answer.

Over the next few days, I’m going to share the most helpful rules of thumb I know. They aren’t going to apply to everyone in all situations. But if you’re looking for guidelines (or guardrails), there are a starting point.

Let’s start with retirement:

Retirement comes first. You can’t get back lost company matches or lost tax breaks, and every $1 you fail to save now can cost you $10 to $20 in lost future retirement income. You may have other important goals, such as paying down debt or building an emergency fund, but you first need to get started with retirement savings.

Save 10% for basics, 15% for comfort, 20% to escape. If you start saving for retirement by your early 30s, 10% is a decent start and 15% should put you in good shape for a comfortable retirement (these numbers can include company matches). If you’re hoping for early retirement, though, you’ll want to boost that to at least 20%. Add 5-10% to each category for each decade you’ve delayed getting started.

Don’t touch your retirement funds until you’re retired. That pile of money can be tempting, and you can come up with all kinds of reasons why it makes sense to borrow against it or withdraw it. You’re just robbing your future self.

Keep it simple–and cheap. Don’t waste money trying to beat the market. Choosing index mutual funds or exchange-traded funds, which seek to match market benchmarks rather than exceed them, will give you the returns you need at low cost. And cost makes a huge difference. If you put aside $5,000 a year for 40 years, 1 percentage point difference in the fees you pay can result in $225,000 less for retirement.