Penelope Trunk The Brazen Careerist

One of the ways I got my nearly disastrous financial life back on track was by reading a lot of economic advice online. It helps to be part of a community of people thinking hard about their values and their money and the alignment of the two. And it helps to read a wide range of opinions.

I also experimented with various online financial tools, and while some were helpful, I realized that there are five common ones to use only with caution:

1. Salary comparison tool

The reason salary comparison tools exist is so people can make sure they're getting paid enough. If you need to use such a tool, however, your career is in trouble.

First of all, most comparison tools give you an average salary within a 25 percent margin of error. If you don't know what you're worth within a 25 percent margin of error, that's a problem.

Why not just compare salaries with friends who are in your field? If you're in a business in which you have no contacts, you're not worth the average amount anyway, because you're so ineffective at connecting with people around you that you're compromising your ability to add value to a company.

Finally, these tools presume an outdated notion that people work only for the money. Sure, money is good, but people rank other things as way more important. So until there's a salary comparison tool that takes flexibility, opportunities for personal growth, and available health care providers into account, they're not worth your time.

2. Cost of living calculator

The problem with this kind of tool is that it gives you information you can't use. You need to know which city will make you happy, not which city will save you $20,000 in housing costs.

Let's say you're thinking of moving from San Francisco to New York City. They're both really expensive to live in, so the difference in your salary isn't going to matter. You should probably think harder about their respective cultures than about money; very few people fit in well in both cities, and most feel like they belong in one or the other. A calculator can't tell you that.

Now let's say you're moving from New York City to Los Angeles. You'll save money on housing, of course, but you'll need a really good car.

In L.A., a BMW is totally reasonable. You'll end up spending more time there than in your apartment. In NYC, however, owning a BMW is commonplace only among millionaires. For most New Yorkers, having such a car is absurd -- they just don't drive enough. But online cost of living calculators don't have a "BMW: yes or no" option.

And what if you're moving from Chicago to, say, Kankakee, Ill.? You can compare home prices and taxes, but here's something a calculator won't tell you: Whether there's a Nordstrom store there. If you have to drive 100 miles to shop anywhere besides Target, then the cost of living calculator is pretty much irrelevant -- the parameters of "living" change significantly depending on the services available where you end up.

3. Stock tips

Can we finally just admit that buying individual stocks is like gambling? Most people simply don't have enough money so that they can afford to put it into individual stocks. Putting your money into a fund gives you much more diversity.

God help you if you do have enough money to invest in a good stock that'll make a big difference in your life, because if you end up losing that money it'll probably make a big difference in your life, too. The odds of you knowing what you're doing in the stock market are slim anyway.

Unless you spend your days studying it, that is, and then you have to ask yourself why you don't spend your days figuring out how to be a star performer at work instead. There are guaranteed higher yearly returns from that, and it's something over which you have control.

So if you really want to believe in yourself, put your money in an index fund and concentrate on your career. That way, you'll get a return on your investment that really will change your life.

4. Renting vs. buying calculator

It used to be that the American dream was about buying a house. Today, the new version of the American dream is about time and personal development -- and the best way to get more time is to not be tied down to a house.

You don't need to worry about repairs and maintenance and earning enough to "buy the most house you can buy." You also have more freedom for personal development if you can move around easily. So it's time to get over the idea of owning a house as the achievement of the American dream -- it's just holding you back.

Before most of us turn 32, our jobs typically last less than two years apiece. Yet it doesn't usually make financial sense to buy a house unless you plan to stay in it for at least five years. And most people who want to make a career change stop themselves because of their financial commitments (read: mortgage). What's wrong with this picture?

Clearly, for a lot of people, buying a house is an unnecessary, career-limiting decision.

5. Retirement calculator

Is there anyone out there who still thinks retirement exists? Moreover, who would want to sit around doing nothing all day?

We already know that being a productive member of society is very important to our well being, so what's the point in loafing around for the last 20 years of your life? Besides, people generally can't fund their retirement anymore, so the whole concept is outdated anyway.

More important, though, is that it doesn't make sense to work really hard earning lots of money when you're young just so you can do what you love when you're old and possibly infirm. Start doing what you love now, before retirement. You probably don't need to do it full time, so you can earn money doing something else.

Nobody needs a magic calculator to tell them how long to wait before they can do what they really want to do. Each of us can live our best life right now, this minute, with no money down.