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Simple Interest: How It Works and How It Differs From Compounding

By Imperialpedia Staff

Simple interest is calculated only on the original principal amount of a loan or deposit, without factoring in any interest that has already accumulated. This produces steady, linear growth over time, in contrast to the accelerating growth curve of compound interest.

The Formula

Simple interest is calculated as: principal × interest rate × time. A $10,000 deposit at a 5% simple annual interest rate earns exactly $500 every year, regardless of how many years have passed, because each year's interest is calculated only on the original $10,000.

Where Simple Interest Is Actually Used

Simple interest is less common for long-term savings and investment products, where compounding is the norm, but it does appear in some short-term consumer loans and certain bond structures, where the more straightforward, predictable calculation suits the product.
IMPORTANT
Over short time periods, the difference between simple and compound interest is often small; over long time periods, compounding pulls meaningfully ahead, which is why the distinction matters most for long-term savings and debt.

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