## FAQs & How-to's

#### What is this calculator for?

This mortgage calculator can be used to find the monthly repayment for an amortizing loan, as well as the term, rate, down payment and principal (loan amount).

#### Can I embed this on my website?

Sure. Embedding is allowed as long as you promise to follow our conditions. Here's the embed code:

 <iframe width="415" height="345" src="http://www.a-calculator.com/mortgage/embed.html" frameborder="0" allowtransparency="true"></iframe> 

#### How can I do the math by hand?

The calculations are based on this formula: \begin{equation*} M = (L-D) \times \frac{i \times (1+i)^n}{(1+i)^n - 1}. \end{equation*}

Where \begin{align*} M &= \text{Monthly repayment,} \\ L &= \text{Loan amount (or principal),} \\ D &= \text{Down payment,} \\ i &= \frac{\text{Interest rate}}{\text{Number of compounding periods per year}} \end{align*} and \begin{align*} n &= \text{Total number of compounding periods.} \end{align*}

As an example, to find the monthly repayment for a \$250,000 loan at 7.5% over 25 years, you would do the following: \begin{align*} L &= 250,000 \\ D &= 0 \\ i &= 0.075 \div 12 = 0.00625 \qquad \text{(Compounded twelve times a year)} \\ n &= 25 \times 12 \end{align*} Then: \begin{align*} M &= (250,000 - 0) \times \frac{0.00625 \times (1 + 0.00625)^{300}}{(1 + 0.00625)^{300} - 1} \\ M &= 1847.48 \end{align*}