15 Percent APR Savings Account Calculator

This calculator helps you determine how much interest you'll earn with a 15% APR savings account. Simply enter your principal amount and the time period, then click Calculate to see your potential earnings and final balance.

How to Use This Calculator

Using this calculator is simple:

Enter the initial deposit amount in the "Principal" field.
Select the time period for your savings (in years).
Click the "Calculate" button to see your results.
Review the interest earned and final balance.
Use the chart to visualize your savings growth over time.

The calculator assumes a 15% annual percentage rate (APR) and monthly compounding. These are typical assumptions for savings accounts, though actual rates may vary based on your financial institution.

Formula Explained

The calculation uses the compound interest formula:

A = P × (1 + r/n)^nt

Where:

A = Final amount
P = Principal amount (initial deposit)
r = Annual interest rate (15% or 0.15)
n = Number of times interest is compounded per year (12 for monthly)
t = Time the money is invested for (in years)

Interest earned is calculated as:

Interest = A - P

This formula accounts for monthly compounding, which means your interest is calculated and added to your balance every month, earning you slightly more than simple interest.

Worked Example

Let's say you deposit $1,000 in a savings account with a 15% APR compounded monthly for 5 years.

Using the formula:

A = 1000 × (1 + 0.15/12)^12×5

A = 1000 × (1.0125)⁶⁰

A ≈ 1000 × 2.0204

A ≈ $2,020.40

Interest earned would be $2,020.40 - $1,000 = $1,020.40.

This example shows how compound interest can grow your savings over time, even with a relatively modest interest rate.

Comparison Table

Here's how your savings grow with different time periods at 15% APR:

Time Period	Principal ($)	Interest Earned ($)	Final Balance ($)
1 year	1,000	157.09	1,157.09
3 years	1,000	513.66	1,513.66
5 years	1,000	1,020.40	2,020.40
10 years	1,000	2,593.74	3,593.74

This table shows how compound interest accelerates your savings growth over longer periods.

Frequently Asked Questions

What is APR?

APR stands for Annual Percentage Rate. It's the yearly interest rate your savings account pays on your balance. A 15% APR means you earn 15% interest annually on your deposited amount.

How is compound interest calculated?

Compound interest is calculated by applying the interest rate to both the initial principal and the accumulated interest of previous periods. This formula accounts for monthly compounding, which means your interest is calculated and added to your balance every month.

What factors affect my savings growth?

The primary factors are the initial deposit amount, the interest rate, and the time period. Higher deposits, higher interest rates, and longer time periods will all result in greater savings growth.