Simple Interest Calculator
Calculate simple interest instantly. Perfect for short-term loans, deposits, and quick interest estimation.
Simple Interest Calculator
Simple Interest Breakdown
SI vs CI — ₹1,00,000 at 10%
| Years | Simple Interest | Compound Interest |
|---|---|---|
| 1 year | ₹10,000 | ₹10,000 |
| 3 years | ₹30,000 | ₹33,100 |
| 5 years | ₹50,000 | ₹61,051 |
| 10 years | ₹1,00,000 | ₹1,59,374 |
| 20 years | ₹2,00,000 | ₹5,72,750 |
What is Simple Interest?
Simple interest is the most straightforward method of calculating interest on a sum of money. It is calculated only on the original principal amount, regardless of the time period. Unlike compound interest, simple interest does not take into account any interest that has been accumulated over previous periods.
Simple interest is commonly used for short-term loans, certain types of fixed deposits, and government-backed lending schemes. In India, many public sector banks offer simple interest on short-term deposits (less than one year), and some educational loans calculate interest on a simple interest basis during the moratorium period.
Simple Interest Formula
The simple interest formula is one of the most basic and widely used formulas in finance:
SI = P × R × T / 100
Where:
- SI = Simple Interest
- P = Principal amount (initial investment or loan)
- R = Annual interest rate (in percentage)
- T = Time period (in years)
Total Amount = P + SI
How to Use This Simple Interest Calculator
- Enter the principal amount — The initial amount invested or borrowed.
- Enter the annual interest rate — The yearly rate offered by your bank or lender.
- Enter the time period — The duration in years for which the money is invested or borrowed.
- Click Calculate — View the simple interest and total amount instantly.
Simple Interest vs Compound Interest
| Feature | Simple Interest (SI) | Compound Interest (CI) |
|---|---|---|
| Formula | SI = P × R × T / 100 | A = P(1 + r/n)^(nt) |
| Calculation base | Original principal only | Principal + accumulated interest |
| Growth pattern | Linear (straight line) | Exponential (curved) |
| Returns | Lower over time | Higher over time |
| Complexity | Simple to calculate | Requires compounding frequency |
| Better for lenders | Yes (lower cost) | No |
| Better for investors | No | Yes (higher returns) |
When is Simple Interest Used?
Short-term loans: Many personal loans and short-term borrowings (less than 1 year) use simple interest. This makes the total repayment amount predictable and easy to calculate.
Car loans: Some banks in India offer car loans on a simple interest basis, especially for shorter tenures. The EMI calculation may use reducing balance, but the interest component is based on simple interest principles.
Fixed deposits (short-term): For FDs with a tenure of less than one year, banks typically pay simple interest. For example, a 6-month FD at 6% will earn exactly 3% (half of 6%) on the principal.
Educational loans: During the moratorium period (course period + 1 year), some educational loans in India are charged on a simple interest basis. After the moratorium, they switch to compound interest.
Overdue payments: When you miss a payment deadline, the penalty interest is often calculated on a simple interest basis on the overdue amount.
Advantages of Simple Interest
- Easy to understand: The formula is straightforward and anyone can calculate it manually.
- Predictable cost: For borrowers, the total interest cost is known from day one.
- Lower cost for short terms: For loans under 1 year, simple interest results in lower total interest compared to compound interest.
- Transparent: No hidden compounding effects — what you see is what you pay.
Limitations of Simple Interest
- Lower returns for investors: If you are investing, compound interest will always yield higher returns over time.
- Not suitable for long-term: Over long periods, simple interest significantly underperforms compared to compound interest.
- Rare in modern banking: Most banks use compound interest for deposits and loans exceeding one year.