Simple Interest Calculator
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Calculate Simple Interest
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Simple Interest Calculator Guide
Simple Interest (SI) is interest calculated only on the original principal amount — not on any previously earned interest. It grows linearly over time, making it easy to predict and understand. It is commonly used in short-term loans, car loans, personal loans, and some fixed deposits.
A principal of ₹1,00,000 at 8% per annum for 5 years:
Principal (P)
The original amount of money invested or borrowed at the start of the period.
Rate (R)
Annual interest rate in percentage. E.g., 8 for 8% per annum.
Time (T)
Duration of the investment or loan in years.
Result: SI
Interest earned or owed. Add to principal to get the total amount payable/receivable.
Simple Interest
Interest is charged only on the original principal. Growth is linear — the same amount of interest is earned each year. Easier to calculate and transparent. Best for borrowers in short-term loans.
Compound Interest
Interest is charged on principal PLUS accumulated interest. Growth is exponential — interest grows faster each year. Better for long-term investors building wealth in mutual funds or FDs.
Vehicle Loans
Car and two-wheeler loans often use simple interest — helping you know exactly how much interest you’ll pay upfront.
Short-Term FDs
Bank fixed deposits for tenures under 1 year typically pay simple interest since there’s no compounding period.
Personal Loans
Many personal loans and credit facilities quote simple interest for transparent EMI calculations over the loan tenure.
Q1: What is the formula for simple interest?
SI = (P × R × T) / 100, where P = Principal, R = Rate per annum (%), and T = Time in years. The total amount = P + SI.
Q2: What is the difference between simple and compound interest?
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus previously earned interest, resulting in faster growth.
Q3: Is simple interest used in home loans?
Most home loans in India use a reducing-balance (compound) method. However, simple interest is used in some overdraft facilities and short-term commercial loans.
Q4: Can simple interest be negative?
No. As long as principal, rate, and time are positive values, simple interest is always positive. A negative result would indicate an error in inputs.