PaisaCalc
Simple Interest Calculator — principal, rate and time
Simple interest is charged only on the original principal, never on interest already earned. Enter the principal, the yearly rate and the time to get the interest and the total amount.
Amortization schedule (year-wise)
| Year | Principal | Interest | Balance |
|---|
How much to invest monthly to reach a target corpus.
Recurring deposit — a fixed amount every month, compounded quarterly.
Public Provident Fund — yearly deposit, compounded annually (15-year lock-in).
Compare the New and Old regimes side by side (FY 2025-26). Enter deductions for the Old regime.
Systematic Withdrawal Plan — how long your corpus lasts while you draw a fixed amount each month.
Sukanya Samriddhi Yojana — deposit yearly for 15 years; matures in 21 years. Interest compounded annually, fully tax-free (EEE).
National Pension System — corpus at 60, then min 40% buys an annuity (pension).
Gratuity under the Payment of Gratuity Act = last salary (Basic + DA) × 15 ÷ 26 × years of service.
Estimate your monthly in-hand from annual CTC (New tax regime, standard assumptions).
How big a loan you may qualify for, from your income and existing EMIs (FOIR method).
What today's money will cost — and be worth — in the future.
How the Simple Interest Calculator works
SI = P × R × T ÷ 100 · Amount = P + SI
- P — principal
- R — rate % per year
- T — time in years
Because the interest never earns interest itself, it grows in a straight line: every year adds the same P × R ÷ 100. Compound interest adds interest on interest, so over the same time it is always at least as much.
Worked example
₹1 lakh at 8% a year for 5 years:
| Interest each year | ₹8,000 |
|---|---|
| Simple interest (5 years) | ₹40,000 |
| Total amount | ₹1,40,000 |
| Compounded yearly instead | interest ₹46,933 |
Simple interest comes to ₹40,000; compounding yearly at the same rate would earn ₹6,933 more.
Load these numbers into the calculator →Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is worked out on the principal only. Compound interest is worked out on the principal plus the interest already added, so it grows faster the longer the money stays in.
How do I work out simple interest for months?
Use the time in years: 6 months is 0.5 year, 18 months is 1.5 years. The slider here moves in whole years; for part-years apply the formula directly.
Related calculators
- FD Calculator — compound interest on a deposit, to compare with simple interest
- CAGR Calculator — the yearly growth rate between two values, on the same tab
- EMI Calculator — interest on a loan repaid in monthly instalments
- Lumpsum Calculator — a one-time amount growing with yearly compounding
More money calculators
- EMI Calculator
- SIP Calculator
- Lumpsum Calculator
- Goal SIP Calculator
- FD Calculator
- RD Calculator
- PPF Calculator
- GST Calculator
- Income Tax Calculator
- Discount & Tip Calculator
- SWP Calculator
- Sukanya Samriddhi Calculator
- NPS Calculator
- Gratuity Calculator
- In-hand Salary Calculator
- Loan Eligibility Calculator
- CAGR Calculator
- Simple Interest Calculator
- Inflation Calculator
Also from CryoSim
PaisaCalc results are arithmetic estimates from the inputs you enter and the formulas shown. They are not financial, investment or tax advice; rates, rules and your own situation vary, so check with your bank, fund house or a qualified adviser before deciding.
