If you're going to invest (whether it's in stocks, real estate or even rare stamps), you have to understand capital gains. After all, whether you win or lose with your picks, mastery of this convoluted part of the tax code can both soften your losses and sweeten your gains.

If you want no more than a good estimate of your 2012 capital gains tax liability, you probably won't need to go further than this page. With our Capital-Gains Tax Estimator you can plug in your gains and losses to figure out your tax hit. Keep in mind that this is also a good strategizing tool to use when you're weighing whether or not to sell some shares right now or later this year.

But if you really want to make this complicated corner of the tax code work to your advantage, we've got more reading for you. The first step is to understand at which rate sales are taxed. That depends on your income from other sources, how long you held the asset and what type of asset it is. (Believe it or not, your prized snow-dome collection would most likely be taxed at a higher rate than, say, your mutual-fund shares.) There's a lot to keep track of: While short-term gains are taxed as ordinary income, the taxes on long-term gains (for assets held more than one year) can range from 0% to 28%. But don't fret. Our feature, At What Rate Will Your Sale Be Taxed? will give you all the details.

Once you've got the different rates straight, you're ready to strategize by using your losses to offset your gains. To do so, you need to calculate your net loss or gain. Our article Tallying Your Capital Gains and Losses will explain all the rules you need to follow.

Still want more? Well, once you've got the basics down, you're ready for some advanced reading.

Keep in mind that the calculator is geared for 2011 tax year sales of traditional investments (like stocks, bonds and mutual funds). And while this worksheet should give you a very good idea of your bill, for a completely accurate estimate, you'll need to fill out Form 8949 and Schedule D (both are available on the IRS Web site).

For gains from other types of investments like collectibles (which are taxed at a maximum rate of 28%) or investment real-estate (which are sometimes taxed at 25%), you'll have to adjust the calculator's output by hand by following the precise rules for that type of asset. (See IRS Publication 544 for all the sordid details.) Also, if you're subject to the alternative minimum tax, or AMT, this calculator won't tell you the whole story. You'll have to fill out Form 6251 (Alternative Minimum Tax -- Individuals) to fully assess your tax situation.