Simple Interest Calculator

The SolversPro Simple Interest Calculator is a free financial tool that calculates total interest earned or paid and final balances on loans, promissory notes, and deposits using the linear principal-rate-time formula.

Quickly calculate simple interest on loans or investments.

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The Formula

Interest = P × r × t

Total Amount (A) = P(1 + rt)

P = Principal amount

r = Annual interest rate (decimal)

t = Time in years

Simple Interest vs. Annual Compound Interest ($10,000 at 6%)

Comparison showing linear growth of simple interest versus exponential compounding acceleration over time.

Timeline Simple Interest Earned Simple Total Balance Compound Total Balance Compounding Advantage
1 Year $600 $10,600 $10,600 $0
5 Years $3,000 $13,000 $13,382 +$382
10 Years $6,000 $16,000 $17,908 +$1,908
20 Years $12,000 $22,000 $32,071 +$10,071

Frequently Asked Questions

Simple interest is calculated solely on the initial principal amount of a loan or investment. Unlike compound interest, it does not factor in accumulated interest from previous periods. It is commonly used for short-term personal loans or automobile loans.

Simple interest only grows based on the original amount invested or borrowed. Compound interest grows based on the original amount PLUS the interest that has already been added. Over long periods, compound interest yields significantly more growth.

Simple interest is often used for auto loans, short-term personal loans, and some types of mortgages. It's also occasionally used for short-term certificates of deposit (CDs) or bonds.

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