Learn what simple interest is and how to calculate it using examples with a simple interest formula. You can also use a simple interest calculator.

Different methods in interest calculation can end up with different interest payments. Learn the differences between simple and compound interest.

To calculate per-diem interest, take the interest rate (be sure to express it as a decimal, so 10% becomes 0.10) and divide by 365 to determine the daily interest rate.

Learn how to calculate the Simple Interest in Excel either for a single entry or a range or entries, between two dates, using this forumula.