Gone are the days when you used your standard calculator to do all sorts of calculations, be it an estimation of your mortgage or converting units. Nowadays, there is a specialized calculator for everything you need. Just enter the numbers and off you go.

Consequently, a number of specialized financial calculators have popped up in the last few years that let you do everything from calculating monthly mortgage payments to complicated income tax calculations. Here are 7 such calculators that we found to be most useful and unique:

1. Mookal:

Calculating refinance and mortgage costs are without a doubt one of the biggest segments of personal finance. Mookal has the simplest and very effective calculators to do that for you. Just enter the basic information like rates, terms e,t,c, and Mookal will show you the complete picture. Mookal also shows you a comparison of how things would look if you re-finance.

2. IRS Withholding Calculator:

We all want to keep this one handy. It is provided by IRS and lets you calculate your income taxes and net pay. Don’t worry, all the information entered is anonymous and all the data is discarded once you exit. This one is applicable to US residents only.

3. CommutePrice:

With the ever-fluctuating price of gas, it is always good to know how much a trip would cost you. Simply enter the number of miles, price per gallon and MPG and calculate the cost of your one-time, weekly or monthly commute. Visit CommutePrice.

4. RePayment Calculator:

This calculator by Federal Reserve helps you estimate how much time and money it will take you to pay off your debt. Mainly geared towards credit cards.

5. PayPal Fee Calculator:

This neat tool helps you calculate the net amount you will receive and the fees you would pay to PayPal for any transaction. Supports multiple currencies. Also has a reverse calculator to see how much money you would have to receive to get a certain net amount.

6. eBay Fee Calculator:

This is an extensive calculator that lets you calculate your eBay fee based on the options, upgrades, discounts and listing details you specify. Also takes into consideration the PayPal fee you would have to pay if the item got sold.  You can use it for eBay auction sites of around 20 countries.

7. Amazon Fee Calculator:

Calculate your seller fee and net income when you list an item on Amazon. Also offers a reverse calculator.