Free Simple Interest Calculator
Work out simple interest in seconds. Enter the principal, rate and time to see the interest and the total amount, or solve in reverse for the principal, the rate or the time.
Interest and total from the principal, rate and time.
Total amount ₹62,000.00
- Principal
- ₹50,000.00
- Rate
- 8% a year
- Time
- 3 years
- Interest
- ₹12,000.00
- Total amount
- ₹62,000.00
Handy for quick checks and quotes. Confirm the final figure with your lender or bank before you rely on it.
Work out simple interest in four steps.
Choose what you want to work out, type your numbers, and read the interest and total. Everything updates as you type.
Pick what to work out
Find the interest, or work back to the principal, the rate or the time. The calculator rearranges the formula for you.
Enter your numbers
Type the principal, rate and time. Switch time between years and months, and choose your currency so the totals read the way you expect.
Read the result
See the interest and the total amount, with a full breakdown that updates as you type.
Copy or reuse it
Copy the whole breakdown in one tap for a quote, a message or your records.
More than just the interest.
Most simple interest calculators only find the interest. This one runs the numbers in every direction, so you can start from whatever you already know.
Find the interest
The classic. Enter the principal, rate and time to see the interest earned or owed and the total amount.
Find the principal
Know the interest, rate and time? Work back to the principal that produced it.
Find the rate
Enter the principal, interest and time to reveal the annual rate of interest.
Find the time
Enter the principal, interest and rate to find how long it takes.
How the simple interest maths works.
The formula behind each mode, with a worked example. The maths is the same in any currency.
Simple interest
SI = P × R × T ÷ 100
Total A = P + SI
Example: ₹50,000 at 8% for 3 years earns ₹12,000, so the total is ₹62,000.
Find the principal
P = SI × 100 ÷ (R × T)
Example: ₹12,000 of interest at 8% over 3 years comes from a ₹50,000 principal.
Find the rate
R = SI × 100 ÷ (P × T)
Example: ₹12,000 on ₹50,000 over 3 years works out to an 8% annual rate.
Find the time
T = SI × 100 ÷ (P × R)
Example: ₹12,000 on ₹50,000 at 8% takes 3 years.
Interest that reconciles itself.
This tool is great for a one-off number. But if you run interest across many loans or deposits, track repayments, and need the books to reconcile cleanly, you want that built into your finance system. That is the kind of ERP and finance software we build at Techliphant, shaped around how your business actually works.
Want interest that grows on itself? Try the compound interest calculator.
Common simple interest questions.
Simple interest is interest worked out only on the original amount you invest or borrow, called the principal. It does not add earned interest back to the balance, so the interest is the same every year. That makes it easy to predict, and it is common on short term loans, car loans and some deposits.
Multiply the principal by the annual rate and by the time in years, then divide by 100. So SI = P × R × T ÷ 100. For example, ₹50,000 at 8% for 3 years earns ₹50,000 × 8 × 3 ÷ 100, which is ₹12,000.
The formula is SI = P × R × T ÷ 100, where P is the principal, R is the annual rate of interest as a percentage, and T is the time in years. The total amount you end with is the principal plus the interest, or A = P + SI.
Simple interest is charged only on the principal, so it stays flat each year. Compound interest is charged on the principal plus any interest already added, so it grows faster over time. Over long periods the gap can be large. Our compound interest calculator shows the difference side by side.
Rearrange the formula to P = SI × 100 ÷ (R × T). If you earned ₹12,000 of interest at 8% over 3 years, the principal was 12,000 × 100 ÷ (8 × 3), which is ₹50,000. Set the tool to Find principal and it does this for you.
Rearrange to R = SI × 100 ÷ (P × T). On a ₹50,000 principal that earned ₹12,000 over 3 years, the rate is 12,000 × 100 ÷ (50,000 × 3), which is 8% a year. Choose Find rate in the tool.
Rearrange to T = SI × 100 ÷ (P × R). To earn ₹12,000 on ₹50,000 at 8%, the time is 12,000 × 100 ÷ (50,000 × 8), which is 3 years. Choose Find time in the tool.
Yes. Switch the time unit to months and the calculator converts it to years for you, because the rate is annual. Six months counts as half a year, for instance.
Yes on both. It is free, there is no sign-up, and it runs entirely in your browser. Nothing you type is sent anywhere or saved, so your numbers stay on your own device.
It is great for a quick check on a loan, a deposit or an invoice. For running interest across many accounts, tracking repayments and keeping the books reconciled, you want that built into your finance system. That is the kind of ERP and finance software we build at Techliphant.
Private by design: this calculator runs entirely in your browser, so nothing you type is uploaded or stored. It is provided free for quick estimates and educational use. For loan agreements and statements, confirm the final figures against your lender or accounting software.
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