How to use Simple Interest Calculator
- Enter the amount borrowed or invested in Principal, for example 50000.
- Enter the yearly rate in Annual rate (%), such as 9.
- Enter the duration in Years. For months, divide by 12, so 6 months is 0.5.
- Press Calculate to see the Total, with the Interest shown underneath.
- Copy the figures or press Reset for another loan or deposit.
Supported formats and limitations
- Input
- Numbers typed into the form (plain digits, no currency symbols or thousands separators)
- Output
- Result on screen, with one-click copy
- Works on
- Any modern browser on Windows, macOS, Linux, Android and iOS. JavaScript must be enabled.
Important limitations
Results use standard formulas and floating-point arithmetic, shown to a sensible number of decimals. They are estimates for planning and do not replace professional financial, tax, medical or legal advice. Banks and institutions may round differently.
Privacy and file processing
Everything runs in your browser. Nothing you enter is uploaded, stored or logged by this website.
About Simple Interest Calculator
The Simple Interest Calculator works out interest charged or earned only on the original principal, with no interest on interest. Enter the principal, the annual rate and the time in years, and it shows the total amount along with the interest portion. It is the classic I = P × R × T calculation taught in school and used for many short-term loans.
People use it to check interest on personal loans between friends and family, gold loans, some agricultural and short-term credit, and simple savings schemes, as well as for exam practice. Part years are allowed, so six months is entered as 0.5. Because the formula is linear, doubling the time or the rate doubles the interest, which makes the results easy to sanity-check.
Features
- Shows total amount and interest separately
- Classic I = P × R × T formula
- Fractional years for loans of a few months
- Durations up to 1000 years and rates up to 10000%
- Plain-language error messages and amounts shown with 2 decimals and Indian digit grouping
Why use it
- Know exactly how much interest to pay or expect
- Settle informal loans fairly and transparently
- Verify textbook and competitive-exam answers
- Quick on mobile with nothing to install
Formula used
Interest = P × r × years; total = P + interest.
Examples
Two-year personal loan
Input: Principal 50000, Annual rate 9, Years 2
Result: Total: 59,000.00
Interest: 9,000.00
Borrowing ₹50,000 at 9% for 2 years costs ₹9,000 in interest.
Six-month deposit
Input: Principal 200000, Annual rate 7.25, Years 0.5
Result: Total: 2,07,250.00
Interest: 7,250.00
Half a year at 7.25% on ₹2 lakh adds ₹7,250.
Simple Interest Calculator: frequently asked questions
What is the formula for simple interest?
Simple interest = Principal × Rate × Time, with the rate written as a decimal and time in years. The total amount is principal plus interest. For ₹1,000 at 5% for 3 years, interest is 1000 × 0.05 × 3 = ₹150 and the total is ₹1,150, which the calculator shows as Total: 1,150.00 and Interest: 150.00.
How do I calculate simple interest for months or days?
Convert the period to years. For 6 months enter 0.5, for 9 months enter 0.75, and for 90 days enter 90 ÷ 365, roughly 0.2466. Lenders may use a 360-day or 365-day year, so the figure in your agreement can differ slightly. The calculator itself only asks for years.
Is simple interest better than compound interest?
It depends on which side you are on. As a borrower, simple interest is cheaper because interest never builds on itself. As a saver, compound interest grows faster over time. For short periods the difference is small; over many years compound interest pulls far ahead for the same rate.
Do banks use simple interest for loans?
Most home, car and personal loans from banks use a reducing-balance method with EMIs, not flat simple interest, so this tool will not match their schedule. Simple interest is common for short-term and informal loans and in exam problems. Always read your loan agreement, and treat this calculator as an estimate rather than financial or legal advice.
Can I find the rate or time instead of the interest?
This calculator solves for interest and total amount only. You can still find the rate with simple rearranging: Rate = Interest ÷ (Principal × Time) × 100. For example, ₹9,000 interest on ₹50,000 over 2 years means 9000 ÷ 100000 × 100 = 9% a year.
Results are estimates for general information, not financial, medical, legal, tax or property advice. Confirm important figures with the relevant institution or a qualified professional.