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Calculate Simple Interest & Total Amount Instantly

Calculate simple interest using the I = P × r × t formula. Enter principal, annual rate, and time period to see interest earned, total amount, daily/monthly/yearly accrual, and a comparison with compound interest.

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How to Use Simple Interest Calculator

How to Use Simple Interest Calculator

  1. Select a Preset (Optional): Click one of the example presets (Short-term Loan, Savings Bond, Personal Loan, Invoice Finance) to pre-fill realistic values.

  2. Enter Principal Amount: Input the starting amount of money — the loan amount or initial investment.

  3. Enter Annual Interest Rate: Input the yearly interest rate as a percentage (e.g., 5.5 for 5.5%).

  4. Enter Time Period: Input the duration of the loan or investment as a number.

  5. Select Time Unit: Choose Years, Months, or Days. The calculator converts to years automatically before applying the formula.

  6. Click Calculate Interest: Press the button to compute your results.

  7. Review Total Amount: See the total amount (principal + interest) highlighted at the top.

  8. Check Accrual Schedule: View interest broken down per day, per month, and per year for cash flow planning.

  9. Compare with Compound Interest: See how much more (or less) compound interest would yield over the same period.

  10. Review the Formula Card: The formula card shows I = P × r × t with your actual values substituted in.

  11. Reset Anytime: Click Reset to clear all inputs and start a new calculation.

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