Simple Interest Calculator

Principal Amount (₹):

Rate of Interest (% per annum):

Time Period (in years):

Money matters can feel tricky, but calculating interest doesn’t have to be one of them. Whether you’re taking a small personal loan, planning for an education expense, or simply curious to see how much your savings can earn, understanding simple interest can save you time and stress. That’s why we’ve built this free Simple Interest calculator or SI calculator.

You can find out exactly how much interest you’ll pay or earn on any amount in just a few clicks. This means no long maths, no confusing spreadsheets, but a quick and accurate answer. Let’s find out more.

Steps to Use Our Simple Interest Calculator

Simple Interest Calculator @ BookMandee

Interest calculations often feel like one of those things best left for later until a repayment date comes knocking. That’s where this Simple Interest calculator comes in handy. It’s a 100% free online tool designed to make life easier for students, parents, small business owners, or anyone handling short-term borrowing or savings. You can get instant, accurate results within seconds.

How to Use This Simple Interest Calculator?

Using this calculator is easy and doesn’t require any technical know-how:

Enter the principal amount (₹) you’re calculating the interest for.
Fill in the rate of interest (%) applicable to your loan or savings.
Select the time period (in years)
Hit the ‘Calculate’ Button.

You’ll instantly see:

Simple Interest (the interest amount payable or receivable)
Total Amount Payable (Principal + Interest)

Also Read: Top Websites to Buy Used Books Online

Why Should You Use an Online Simple Interest Calculator Instead of Manual Calculation?

To avoid errors that happen with manual calculations
To save time and get instant results, even for multiple entries
To quickly check different rates and periods to find the best option
To estimate your monthly payment if you plan to pay for a loan in instalments

What is Simple Interest? (And Why Should You Care?)

Simple Interest might sound like something straight out of a maths class. However, it’s actually one of the easiest and most useful concepts in personal finance. It’s a way to calculate interest on a loan or savings where the interest is charged only on the original amount borrowed or invested, not on accumulated interest like in compound interest.

So, if you’ve ever wondered how to calculate simple interest without headaches, this page is for you.

Simple Interest Formula (Easy to Remember)

The formula is super easy:

SI = (P × R × T) / 100

Where:

P = Principal (the original amount)
R = Rate of Interest (%) per year
T = Time in years

This is the same formula we use in our simple interest loan calculator so you don’t have to manually punch numbers every time.

A Quick Example (Relatable and Real-Life)

Let’s say you take a small education loan of ₹10,000 at an annual interest rate of 8% for 2 years.

Using the formula:
SI = (10,000 × 8 × 2) / 100 = ₹1,600

That means you’ll pay ₹1,600 as interest, and your total repayment will be ₹11,600.

Where Do People Use Simple Interest?

Education loans as many student loans for short-term courses or skill training
Small personal loans while borrowing from banks, cooperatives, or even friends
Fixed income savings to calculate returns

If you like to track these numbers on your own, we even show you how to calculate simple interest in Excel later in this guide. It’s perfect if you want to keep your own little budget sheet at home.

How to Calculate Simple Interest – 3 Easy Ways

Let’s break down how to calculate simple interest in three simple ways: manually, using Excel, and with our free online SI calculator.

Manual Calculation (The Old-School Way)

If you like doing things by hand, here’s how:

Formula: SI = (P × R × T) / 100

Example:

Borrowed amount (P) = ₹20,000

Rate of interest (R) = 7%

Time period (T) = 2 years

SI = (20,000 × 7 × 2) / 100 = ₹2,800

So, you need to pay ₹2,800 as interest and ₹22,800 in total repayment.

Using Excel (For the DIY Planners)

Want to keep track of multiple loans or savings plans? Excel is your friend.

Open Excel and type this formula in a cell:
= (Principal * Rate * Time) / 100
Replace Principal, Rate, and Time with numbers.

Example:

Type = (20000 * 7 * 2) / 100 → Excel instantly gives ₹2,800.

Using Our Free Online SI Calculator (The Smartest Way)

Our Simple Interest calculator takes away all the hassle:

Enter your Principal (₹), Interest Rate (%), and Time (Years).
Hit ‘Calculate’.
Get results in seconds: Simple Interest amount + Total Payable amount.

Simple Interest EMI – Is It the Same as Loan EMI?

When you hear ‘EMI’, you might think of regular bank loans where interest keeps adding up on the balance every month (that’s compound interest). But did you know some loans still use simple interest?

With simple interest loans, the interest is calculated only on the original loan amount, not on the running balance. This means:

The total interest payable is fixed in advance.
Your monthly EMI (Equated Monthly Instalment) is generally lower and more predictable.

Example:

You take a loan of ₹10,000 at 8% per year for 2 years.

Interest = (10,000 × 8 × 2) / 100 = ₹1,600
Total repayment = ₹10,000 + ₹1,600 = ₹11,600
Monthly EMI = ₹11,600 ÷ 24 = ₹483.33

No surprises, no recalculations – just a flat interest model that’s easier to understand.

Our Simple Interest calculator lets you see both the total interest and a breakdown of monthly EMI in one go, making budgeting simpler for students, parents, and small businesses alike.

Sample EMI Table for Quick Reference

Loan Amount (₹)	Interest Rate (%)	Tenure (Years)	Total Interest (₹)	Monthly EMI (₹)
5,000	8	1	400	450
10,000	10	2	2,000	500
15,000	7	3	3,150	506

(EMIs are approximate and based on simple interest calculation.)

Who Should Use an SI Calculator?

You don’t have to be a finance expert to use this Simple Interest calculator. It’s built for anyone who wants quick, clear answers without the hassle of manual calculations. Here’s who benefits the most:

Students & Parents

Planning to take an education loan? This calculator helps you see how much interest you’ll pay over the loan period.

Personal Loan Borrowers

Taking a small personal loan from a bank, NBFC, or even a friend? Use the simple interest loan calculator to know exactly what your total outgo will be.

Small Business Owners & Shopkeepers

Need quick cash for inventory or short-term expenses? Many small loans still use simple interest. With our calculator, you’ll know your cost upfront and plan repayments better.

Savers & Investors

Even some fixed income schemes use simple interest. If you want to see how much your savings will earn, this SI calculator can give you instant results.

Anyone Tracking Multiple Loans or Budgets

If you’re the kind of person who loves planning in Excel or budgeting for multiple payments, this tool saves you time and ensures your numbers are accurate.

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