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Simple Interest Calculator

Find the simple interest and the total amount for any principal, rate and time. Enter the amount borrowed or invested, the annual interest rate and the time in years, and this free simple interest calculator applies I = P × R × T instantly and privately.

Principal (P)

Annual rate (%)

Time (years)

What is simple interest?

Simple interest is the interest earned or charged on a principal amount without compounding — the interest is calculated only on the original sum each period, never on previously earned interest. The formula is I = P × R × T, where P is the principal, R is the annual interest rate expressed as a percentage, and T is the time in years. The total amount is the principal plus that interest.

Because there is no compounding, simple interest grows in a straight line rather than a curve, which makes it easy to predict and compare. It's commonly used for short-term loans, bonds, car finance, some savings accounts and sometimes bank deposits. For example, 10,000 at 5% for 2 years earns 10,000 × 5% × 2 = 1,000, giving a total of 11,000.

This calculator does all of that in your browser, showing the interest and total in your local currency at a glance.

How to use the simple interest calculator

Enter the principal — the starting amount of money.
Enter the annual interest rate as a percentage (for example 5 for 5%).
Enter the time period in years.
Click Calculate to see the simple interest and the total amount.

Example

Enter a principal of 10,000, a rate of 5% and a time of 2 years. The calculator shows interest of 1,000 and a total of 11,000, worked out as 10,000 × 5 × 2 / 100. Change the time to 3 years and the interest becomes 1,500 with a 11,500 total.

Who is this simple interest calculator for?

Simple interest shows up wherever money is borrowed or lent for a set period without compounding — loans, bonds, deposits and many short-term products. This calculator helps students, couples, professionals and retirees work out the interest and total in seconds.

Students and young adults: Learning finance, or borrowing for a first car or phone, becomes clearer when you can see the interest yourself. This calculator shows exactly how much a loan costs over time, so a student can compare offers before signing.
Couples: Planning a wedding, a car or a short-term personal loan means knowing the real cost. Couples use this to work out the interest a lender will charge and the total amount to repay before they commit.
Salaried professionals: Short-term credit, car finance or a deposit with a clear maturity date all rest on simple interest. Professionals estimate the interest on a fixed deposit or a bond to judge whether the return is worth the lock-in.
Retirees: Retirees often keep money in fixed deposits and bonds with a simple interest return. This calculator shows the interest and total for a specific rate and period, so they can plan their income with confidence.

Simple interest table — ₹10,000 principal

This table shows the interest and total amount for a principal of ₹10,000 across a few common rates and time periods, using I = P × R × T. Longer terms and higher rates both add up quickly.

Principal	Annual rate	Time	Simple interest	Total amount
₹10,000	4%	1 year	₹400	₹10,400
₹10,000	5%	2 years	₹1,000	₹11,000
₹10,000	6%	3 years	₹1,800	₹11,800
₹10,000	8%	5 years	₹4,000	₹14,000
₹10,000	10%	10 years	₹10,000	₹20,000

Interest = principal × rate × time ÷ 100; total = principal + interest. ₹10,000 at 5% for 2 years earns ₹1,000, for a total of ₹11,000.

Common use cases

Working out the interest owed on a short-term personal or car loan.
Estimating the return on a fixed deposit, bond or simple savings product.
Checking how much a borrower really pays before signing a loan agreement.
Comparing simple and compound interest to see which grows faster.

Pro tips

Simple interest grows in a straight line, so time matters just as much as the rate.
Use a bank or finance calculator for long-term investments where compounding applies.
Convert months to years before calculating (6 months = 0.5 years) for accurate results.
Always compare the effective rate, since fees and charges can make a 'cheap' loan expensive.

FAQ

What is the simple interest formula?

I = P × R × T, where P is the principal, R is the annual rate in percent and T is time in years. The total amount is P + I.

How is simple interest different from compound interest?

Simple interest is earned only on the original principal. Compound interest is also earned on previously accumulated interest, so it grows faster over time.

What is total amount in simple interest?

It is the principal plus the interest: Total = P + (P × R × T). For 10,000 at 5% for 2 years the total is 11,000.

How do I convert months to years?

Divide the months by 12. Six months becomes 0.5 years, which is the T used in the formula.

Is higher principal always more interest?

Yes, for a given rate and time the interest is directly proportional to the principal.

What currencies can I use?

The calculator formats results as Indian rupees (INR), but you can read the numbers in any currency by treating them as your own.

Is this calculator free?

Yes — it is free, requires no signup and calculates everything locally in your browser.

When is simple interest used?

It is used for short-term loans, car and personal finance, bonds, many fixed deposits and situations with a clear maturity date.

Can I find an unknown variable?

Rearrange the formula to solve for the missing one: to find the rate, divide the interest by (P × T).