Simple Interest Calculator
Calculate interest earned or owed without compounding.
About This Calculator
The simple interest calculator shows how much interest builds on a starting amount when interest is not added back into the balance. It is often used for short-term borrowing, basic lending examples, and quick estimates.
Formula: Simple Interest = Principal x Rate x Time. The rate should be entered as a yearly percentage, and the time should be entered in years.
Example: If you invest 10,000 at 5% per year for 3 years, the interest is 1,500 and the final amount is 11,500.
Simple interest is easiest to understand because the interest is always based on the original principal only. It does not grow faster over time the way compound interest does.
When Simple Interest Is Used
Simple interest is often used in classroom examples, short-term loans, and basic comparisons. It can also be useful when you need a fast estimate without working through more detailed compounding rules.
If your bank account, investment, or loan compounds daily, monthly, or yearly, this calculator will not reflect that extra growth. In that case, the compound interest calculator is the better tool.
Related Calculators And References
If you need a compounding result, use the Compound Interest Calculator. If you are comparing borrowing costs, the Loan Payment Calculator and EMI Calculator may be more useful.
For background reading, see the Investor.gov explanation of compound interest to understand when simple interest and compound interest produce different results.