This post is brought to you by BlackFri.com, where you can see all of the Black Friday Ads before they come out in the Thanksgiving Day paper.

“8% interest is good, right?” I asked my Dad.

“Well, it’s good for the bank,” he said. “Better than a higher rate though, so it could be worse.”

I don’t know much about interest rates and loan payments, and I don’t think I’m alone. I’m a 20-something college grad, and while I graduated debt free, many of my friends are in six-figures of college debt. I was shocked to discover my boyfriend’s $150,000 in student loans would cost over $50,000 in interest payments. That means he’ll pay back $200,000 total – effectively a 33% markup on the original loan amount. My friends and many other students aren’t aware of how quickly interest can accumulate on loans. (Some have asked about bankruptcy to deal with college debt!)

I found three debt calculators that show the size of loan payments, the impact of interest, and your overall loan cost.

What are the best college debt calculators?

How Long for How Much? The CNN Money Student Debt Calculator is an easy way to determine how much interest and how long you will be paying off your loans. Simply, enter the total loan amount, monthly payment, and interest rate. The Calculator will then tell you how long it will take to pay your loans down to the month and the amount of interest you will pay over this time. This is a great way to see how beneficial increasing your loan payments can be. On a $40,000 loan – equivalent to one year of college for some – it will take three years and 11 months to pay off the loan if you pay $1,000 per month at 8% interest. You will also pay $6,679 in interest! By increasing the payment by just $200 a month, you decrease your interest by more than $1,000!

Multiple Loans Fix. The best part about the PayBackSmarter Calculator is that it is customizable to your exact loans. It is the only calculator I found for use with multiple loans! You are able to add multiple loans, choose the loan type, and interest rates. This was the most convenient calculator for me, as I was using my boyfriends five loans as an example. For those who want to see the impact of multiple loans, this is the calculator for you! The calculator also shows different options for paying back your loans such as graduated repayment, consolidation, and extended repayment. If you’re not sure what your best option is for paying back your loans, this is an easy way to weigh the pros and cons of different methods.

How Do Extra Payments Effect Your Debt? – This is a great tool for those trying to make a plan to pay off college loans quickly. By using the BankRate College Planning Calculator you are able to see the effect of increasing your payments and/or adding an extra payment every few months. After you enter your loan information you are given an Amortization chart. Amortization is the the process of decreasing a loan amount of over time. The chart shows the impact of each payment you make. It indicates what portion is going towards reducing your principal balance and what is going towards interest month by month. I found this amazing! You can see in real time how and when your loans and interest will decrease. Again, it makes you realize the impact of paying back your loans quickly.

What’s your favorite debt calculator?