Simple Interest Calculator
Calculate interest without compounding. Useful for short-term loans, bonds, and non-compounding investments.
Flat Rate Calculator
Breakdown
What is Simple Interest?
Simple interest is a quick method of calculating the interest charge on a loan or the return on an investment. Simple interest is determined by multiplying the daily interest rate by the principal by the number of days that elapse between payments.
Unlike compound interest, where interest is added to the principal to earn more interest, simple interest is calculated only on the original principal amount.
The Formula
The standard formula for calculating simple interest is:
- I: Interest Earned/Owed
- P: Principal Amount
- r: Annual Interest Rate (decimal)
- t: Time Period (in years)
To find the Total Amount (A), you simply add the interest back to the principal: A = P + I.
Real-World Examples
1. Car Loans
Many auto loans use simple interest. If you pay early, you save money because interest is calculated daily on the remaining balance.
2. Bonds (Coupon)
A bond that pays a 5% coupon annually pays exactly 5% of the face value each year, regardless of accumulated value.
3. Personal Loans
Short-term personal loans often use simple interest to make the total repayment amount predictable.
4. Late Fees
If you owe money to a utility company, late fees are often calculated as simple interest on the overdue amount.
Disclaimer & Legal Notice
Calculations: This tool assumes a standard 365-day year for daily interest calculations. Some financial institutions may use a 360-day year (banker's year), which results in slightly higher interest charges.
Not Financial Advice: This calculator is for educational purposes only. Always check your loan agreement or investment contract for the exact interest calculation method used.
Privacy: Data entered is processed locally in your browser and is not stored.