Definitions
Understand exactly what every input and output in our calculators means — in plain English, with no jargon.
Calculator Inputs
Principal / Initial Investment
The starting amount of money you invest or borrow. In loan calculators, this is the amount borrowed. In investment calculators, this is your opening balance.
Annual Interest Rate / Expected Return
The yearly percentage rate applied to your balance. For loans, this is the rate charged by the lender. For investments, this is the assumed annual growth rate.
Time Period / Tenure
The duration of the loan or investment, usually expressed in years or months. Longer periods result in more growth (investments) or more interest paid (loans).
Compounding Frequency
How often interest is calculated and added to your balance. Daily compounding earns slightly more than monthly, which earns more than annual — all at the same nominal rate.
Monthly Contribution / SIP Amount
The fixed amount added to an investment every month. Regular contributions dramatically accelerate wealth building through consistent dollar-cost averaging.
Inflation Rate
The assumed annual rate at which prices rise. Used in retirement and FIRE calculators to show the 'real' purchasing power of future money.
Down Payment
The upfront cash portion paid when purchasing a property or vehicle. A higher down payment reduces the loan amount, monthly payment, and total interest paid.
Step-Up Rate
The annual percentage by which you increase your SIP contribution each year. A 10% step-up means if you invest ₹5,000 in Year 1, you invest ₹5,500 in Year 2.
Calculator Outputs
Future Value (FV)
The projected total value of an investment at a future date, based on assumed growth rates and contributions. This is the headline number in most investment calculators.
Total Invested / Total Principal
The sum of all money you have put into an investment — your initial amount plus all subsequent contributions. Excludes any growth or interest earned.
Wealth Gained / Interest Earned
The difference between Future Value and Total Invested. This is the money your money made for you — the power of compound interest.
Absolute Return
Total percentage gain calculated as: (Wealth Gained / Total Invested) × 100. Shows total return without accounting for the time taken.
CAGR (Compound Annual Growth Rate)
The annualised return rate that would produce the same end result as the actual investment performance. Useful for comparing investments over different time periods.
Monthly EMI / Payment
The fixed amount you pay every month on a loan, covering both interest and principal repayment. Remains constant throughout the loan term for fixed-rate loans.
Total Interest Payable
The total amount of interest you will pay over the entire loan term. Calculated as (Monthly Payment × Total Months) − Principal.
FIRE Number
The total portfolio value needed to safely retire and live off investment returns indefinitely. Typically calculated as Annual Expenses × 25, based on the 4% safe withdrawal rate.
Rates & Percentages
Nominal Rate
The stated or advertised interest rate before accounting for compounding. A 12% nominal rate compounded monthly is different from 12% compounded annually.
Effective Rate (EAR / APY)
The actual annual return after accounting for compounding within the year. Always higher than the nominal rate when compounding occurs more than once per year.
Real Return
Investment return after adjusting for inflation. If your investment returns 8% and inflation is 3%, your real return is approximately 5%.
Marginal Tax Rate
The tax rate applied to the last dollar of income earned. In progressive tax systems, each income bracket has its own rate — your marginal rate is the highest bracket you reach.
Effective Tax Rate
The average tax rate you actually pay on your total income, calculated as Total Tax Paid ÷ Total Taxable Income. Always lower than your marginal rate in progressive systems.
Withdrawal Rate
The percentage of your investment portfolio you withdraw each year in retirement. The widely cited '4% rule' suggests 4% is sustainable over a 30-year retirement.
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