💰 Simple Interest Calculator
Calculate interest on loans and investments using the simple interest formula
📊 Investment/Loan Details
The initial amount of money invested or borrowed
The annual rate of interest applied to the principal
Enter at least one time field
📊 Interest Calculation Results
Total Amount
—
Principal Amount
—
Simple Interest Earned
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Annual Interest Rate
—
Time Period
—
Rate Comparison
| Interest Rate | Interest Earned | Total Amount | Increase |
|---|---|---|---|
| Enter details to see comparison | |||
📅 Amortization / Payment Schedule
Choose Year or Month view to see how interest and balance grow over the full time period.
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Enter your details and click "Calculate Interest" to see the growth schedule
🧮 Understanding Simple Interest
Simple interest is calculated only on the principal amount (the original sum of money). It does not compound, meaning interest is not earned on previously accumulated interest.
I = P × R × T
Where: I = Simple Interest, P = Principal, R = Rate (as decimal), T = Time (in years)
A = P + I
Where: A = Total Amount, P = Principal, I = Simple Interest
When Simple Interest is Used:
- Short-term loans and investments
- Auto loans and some personal loans
- Savings accounts with simple interest
- Bonds and fixed-income investments
Simple vs Compound Interest:
- Simple Interest: Interest calculated only on principal
- Compound Interest: Interest calculated on principal + accumulated interest
- Compound interest typically yields higher returns over time
Use this calculator to quickly determine the simple interest for any loan or investment. Simple interest is straightforward and easy to calculate, making it useful for understanding basic financial returns.
🧭 How to Use the Simple Interest Calculator
- 1. Select your currencyChoose USD, INR, EUR, GBP, JPY, CAD, or AUD from the currency dropdown at the top so results display in the correct format.
- 2. Enter the Principal AmountType in the original amount you are investing or borrowing (for example, 5000).
- 3. Enter the Annual Interest RateAdd the yearly interest rate as a percentage (for example, 5 for 5%).
- 4. Set the Time PeriodFill in Years, Months, and/or Days — you only need to enter at least one of these fields.
- 5. Click "Calculate Interest"Press the button (or hit Enter in any field) to instantly see your total amount, interest earned, and a rate comparison table.
- 6. Switch between Year and Month viewUse the "Year View" or "Month View" toggle above the schedule to see the interest and balance broken down annually or for every single month of the term.
- 7. Reset anytimeClick "✕ Reset" to clear all fields and start a new calculation.
❓ Frequently Asked Questions
What is simple interest?
Simple interest is interest calculated only on the original principal amount, using the formula I = P × R × T. It does not grow on top of previously earned interest.
How is simple interest different from compound interest?
Simple interest is earned only on the principal, while compound interest is earned on the principal plus any interest already accumulated, which usually results in higher overall returns over time.
Can I use this calculator for both loans and investments?
Yes. Enter the principal, rate, and time period, and the calculator will show the total interest and final amount whether you are tracking a loan balance or an investment's growth.
What is the difference between the Year and Month schedule view?
The Year view summarizes interest and balance at the end of each year. The Month view breaks the entire term down month by month, showing every month's cumulative interest and running balance.
Does the calculator account for leap years or exact days?
Day-based time entries are converted using a 365-day year for simplicity. For most everyday estimates this is accurate enough, but exact banking calculations may vary slightly based on the day-count method used.