# Calculating Interest on an Annuity

If you want to grow your money, one option is to invest the money in an annuity. An annuity is product that provides regular payments in exchange for a lump sum. Keep reading to learn more about annuities and how you can calculate the interest on an annuity.

## Annuities Explained

An annuity is a financial product that provides future payments in exchange for a current investment. Fixed and variable are two types of annuities.

A fixed annuity provides a specific number of regular payments in exchange for a stated investment. You can make the required investment in one lump sum or in installments. It's a safe, low-risk option with a specific interest rate, notes Investopedia. You can begin receiving payments as soon as you buy the annuity (an immediate annuity), or you may defer the payments until a later date so that your money has time to grow (a deferred fixed annuity). Fixed annuities are ideal for individuals who prefer the stability of a regular payment, as stated by Investopedia.

Variable annuities don't provide specific payouts. Instead, you invest the money in certain investments inside the annuity. The amount of your payments ultimately depends on the performance of your investments. In some variable annuities, it's possible to lose money, according to Investopedia.

## Calculating the Interest on a Fixed Annuity Yourself

The formula you'll start with is A=P(1+rt), notes CalculatorSoup. A is equal to the total amount of accrued interest and principal. P is equal to the initial amount of the investment, t is equal to the term of the annuity and r is equal to the annual interest rate as a decimal.

You'll need to solve the equation for r. To do this, you need to first rearrange the equation so that it reads r=(1/t)(A/P-1). If A equals $10,500, P equals $10,000 and t equals one year, put these numbers into the equation so that it reads r=(1/1)($10,500/$10,000-1). So, $10,500/$10,000 is 1.05, and that number minus 1 is .05. Once you solve the equation, you get an interest rate (r) of 0.05 or 5 percent.

It's possible to find the amount of interest using the formula I=prt. Here, I is the amount of interest, p is the principal, r is the interest rate and t is the time. The total amount of interest for year one using the numbers above is 0.05 multiplied by $10,000 multiplied by one year. This yields interest of $500.

## An Easier Option for Calculating the Interest Rate on an Annuity

The above method is a little arduous if your math skills are rusty or if you want to calculate the interest rate for multiple annuities. An alternative is to use an online calculator that determines the interest rate and interest payment for you. This option saves time and is accurate. You can even customize what information you input to calculate other details about the annuity, states Bankrate.

## The Interest Rate Doesn't Tell the Whole Story

It's easy to see a high interest payment and get excited about the prospect that your money will earn such a great return. However, it's important to consider the costs associated with buying the annuity. Some annuities have annual fees and maintenance expenses that can decrease your total return. When comparing different annuity options, take the costs into account when calculating your effective interest rate.

## When to See a Professional

If you're a beginner, it can be difficult to properly compare annuities on your own because many come with a plethora of terms, conditions and fees that affect your final net payout. A financial adviser can take all of these items into account when exploring the appropriateness of a potential annuity for your financial situation.