Wouldn't life be grand if you could get the answers to the following questions:

  • Should I pay off debt or invest in savings?
  • Should my spouse work, too?
  • Is a lower rate worth the annual fee on a credit card?
  • What will it take to pay off my loan balance?
  • Should I pay points to lower the rate on my mortgage?
  • How much will my savings be worth 20 years from now?
  • What will it take to save for a college education?
  • Should I use a home equity loan or an auto loan to buy a car?
  • Am I saving enough for retirement?
  • How much will Social Security provide?
  • What IRA am I eligible for?
  • Which is better: a rebate on a new car purchase or special dealer financing?

Well, if The Motley Fool likes to do anything, it's make your life grander. To that end, we've updated and expanded our roster of financial calculators. We now offer more than 100 (free!) calculators organized under the following categories: credit/budget, home, saving, college, equity credit line, retirement, IRAs, bonds, and auto.

Using financial calculators can prove enlightening. A visit to the "What's it worth to reduce my spending" calculator indicates that a 40-year-old could add $115,000 to her retirement savings by spending $50 less a month at Home Depot, $50 less a month at restaurants, and $2 less a day on coffee (and earning 8% on the savings).

We've also added a new feature: You won't have to re-input all your information each time you use a calculator. Fill out the "Am I saving enough for retirement?" calculator today, pull it up again some other time, and your information will still be there. (The calculators, which are provided by FinanCenter, are pre-populated with default settings. We couldn't help noticing that, for the retirement calculators, the default ages are 37 for one spouse, 23 for the other. Perhaps someone at FinanCenter is having a midlife crisis.)

Financial calculators have their limitations. In many cases, users must make assumptions about tax rates and investment returns a few decades away. Those assumptions will most likely prove wrong. So don't base your retirement plan on a 10-minute tussle with a calculator. However, when it comes to such endeavors as comparing loans, analyzing a budget, and deciding between a taxable and tax-free bond, hard numbers can prove very persuasive.