NerdWallet is one of our favorite sites when it comes to personal finance. It's an incredible source of information for anyone who wants to learn about personal finance the easy way, and everyone should bookmark it.

We've covered the site before, highlighting its usefulness for picking out the best health insurance plan and comparing savings accounts online. Now we want to bring its retirement calculator to your attention.

The tool is extremely simple to use:

• Input your current age.
• Input your desired retirement age.
• Input your annual pre-tax income.
• Input how much savings you have right now.
• Input your retirement savings rate.

NerdWallet takes this information, makes a few assumptions, and tells you how "on track" you are towards retiring at the age you want to retire. It presents a breakdown of all the information, and you can adjust things to see how they impact your track.

For me, doubling my savings rate from $500 per month to $1,000 per month changed my retirement age from 73 to 61. By sacrificing a little bit every month, I can essentially add 12 years onto my life!

Click here for the retirement calculator.

Note that this tool is a bit simplistic and you shouldn't make any big decisions based on the results. However, it's a good way to see where you stand and will point you in the right direction.

When do you want to retire? How "on track" are you? Did you find the tool helpful? Let us know in the comments below!

Image Credit: Savings via Shutterstock