Methodology

Every MoneyMetric calculator runs entirely in your browser using pure, separately tested calculation functions. This page documents what each one calculates and the assumptions it makes, so you can check any result yourself. Calculator pages also show their formula and a worked example.

Principles shared by every calculator

• Standard formulas. Loans use the reducing-balance method with monthly compounding, the method used by Indian lenders for home, car, personal and education loans.
• Tested. Each calculation module has automated tests against hand-worked reference values, edge cases (zero, negative, missing and very large inputs, 0% interest) and checks that results are never NaN, infinite or negative where that would be meaningless.
• No hidden data. Rates, prices and returns are entered by you. Default values are illustrative starting points, not market rates or offers. The only external references are listed below, with dates.
• Rounding. Calculations use full precision internally. Results are displayed rounded to the nearest rupee (EMIs also to the paisa where shown). Lenders and payroll systems may round differently.

Loans and EMI

EMI, Loan and Home Loan EMI calculators

The EMI Calculator, Loan Calculator and Home Loan EMI Calculator use EMI = P × r × (1 + r)ⁿ ÷ [(1 + r)ⁿ − 1], where P is the loan amount, r the annual rate ÷ 12 ÷ 100 and n the number of monthly instalments. At 0% the EMI is P ÷ n. Amortization schedules apply each month's interest to the outstanding balance and adjust the final instalment so the balance ends at exactly zero.

Car Loan Calculator

The Car Loan Calculator takes the loan as the on-road price minus your down payment and applies the same EMI formula. Total upfront cost adds any processing fee and other upfront costs you enter; total cost of the car adds every EMI. The optional affordability check compares the car EMI, and all EMIs together, with your take-home pay using rough planning bands (up to 10%, above 10% to 20%, above 20%). These bands are a planning heuristic, not a lending rule.

Loan Prepayment Calculator

The Loan Prepayment Calculator works out the EMI that repays your outstanding balance over the remaining tenure, then simulates the loan month by month with and without prepayments. Lump sums and extra monthly payments reduce principal after that month's EMI. With “reduce tenure” the EMI stays fixed; with “reduce EMI” it is recalculated after each lump sum over the months left in the original tenure, while extra monthly payments always shorten the loan. Any prepayment fee you enter is a percentage of each amount prepaid and is subtracted to give the net saving. The prepay-versus-invest illustration grows the same lump sum over the same period at the loan rate (guaranteed) and at your assumed return (uncertain, optionally after tax on gains).

Buying a home

Home Loan Calculator

The Home Loan Calculator takes the loan as property price minus down payment, LTV as loan ÷ price, and total upfront cash as the down payment plus any stamp duty, registration and other costs you enter.

Home Loan Eligibility Calculator

The Home Loan Eligibility Calculator first finds the largest EMI you can take on: combined take-home income × an adjustable FOIR (fixed obligations to income ratio, 50% by default) minus existing EMIs and other fixed obligations. It converts that EMI into a loan amount as the present value of the monthly payments, EMI × [(1 + r)ⁿ − 1] ÷ [r(1 + r)ⁿ]. The tenure is the lower of the one you choose and the years left until an adjustable retirement age (60 by default). The property budget divides the loan by the lower of your LTV assumption and the RBI limit for that loan size. FOIR and the retirement-age cap are common lender practice, not regulation, and vary between lenders.

Home Affordability Calculator

The Home Affordability Calculator estimates a comfortable budget from your own finances rather than a lender's rules. For each scenario (Conservative, Balanced, Aggressive) the new EMI is the lower of (a) your take-home income × that scenario's EMI-to-income ratio minus existing EMIs and (b) what is left each month after expenses, investments, existing EMIs and ownership costs. That EMI is converted into a maximum loan with the present-value formula. Cash for the purchase is your savings minus the emergency fund you want to keep. The maximum price is the highest price where the loan stays within both the EMI-based limit and the LTV limit, and the down payment plus purchase costs fit within that cash. The ratios are adjustable planning rules of thumb, not recommendations.

Property Purchase Cost Calculator

The Property Purchase Cost Calculator adds every one-time cost of buying to the agreement value: stamp duty, registration (with an optional cap), GST for under-construction homes, brokerage, legal fees, society deposits, other charges and upfront loan charges. Stamp duty and registration use only the rates or amounts you enter — no state rates are built in — applied to the property price or to a higher circle or guidance value if you enter one. Upfront cash is the down payment plus all these costs; total purchase cost is the price plus the costs, excluding loan interest. Fees are treated as inclusive of GST.

Rent vs Buy Calculator

The Rent vs Buy Calculator follows two households with the same starting cash and the same monthly budget, month by month, for up to 30 years. The buyer pays the down payment, purchase costs, the EMI, and maintenance and ownership costs that rise each year. The renter invests the upfront cash and pays rent that rises each year. Whichever side spends less in a month invests the difference at your expected return, compounded monthly at the equivalent effective rate. The buyer's net position is the appreciated home value minus the outstanding loan and selling costs, plus any investments; the renter's is their portfolio. Tax effects, rent deposits and moving costs are excluded.

Investing

SIP Calculator

The SIP Calculator treats each instalment as invested at the start of the month and compounds it at the expected annual return ÷ 12: FV = P × [(1 + i)ⁿ − 1] ÷ i × (1 + i). The return is an assumption you choose, not a forecast, and results are before tax and exit loads.

Salary and tax

Salary Calculator

The Salary Calculator starts from CTC and removes employer PF (12% of basic, or of basic up to ₹15,000 a month) and, if included, gratuity (4.81% of basic) to get gross salary. It then deducts employee PF, professional tax as entered, other deductions, and income tax estimated under the selected regime. The tax estimate covers the standard deduction, the section 87A rebate with marginal relief, surcharge with marginal relief, and 4% health and education cess. Tax is rounded to the nearest rupee and spread evenly over 12 months. Other income, perquisites, variable pay and employer NPS contributions are not modelled.

External references and when they were checked

• Income tax slabs (FY 2026-27 (AY 2027-28), resident individuals below 60 years of age): from the Income Tax Department — tax slabs for individuals; AY 2026-27 rates; unchanged for FY 2026-27 by Budget 2026; verified 6 October 2026. Last verified 6 October 2026.
• Home loan loan-to-value limits: the Reserve Bank of India's general slabs for housing loans to individuals — 90% for loans up to ₹30 lakh, 80% above ₹30 lakh up to ₹75 lakh, and 75% above ₹75 lakh. Used for indicative checks only; lenders may apply stricter limits.
• GST on under-construction homes: 5% (1% for affordable housing) without input tax credit, as notified by CBIC; ready-to-move homes with a completion certificate do not attract GST. Checked 6 October 2026.
• Provident fund: 12% employee and employer contributions on basic wages, with the ₹15,000 monthly wage ceiling as an option, per EPFO rules.

Stamp duty, registration charges, professional tax and lender-specific norms differ by state or lender and change over time, so the calculators ask you to enter them instead of assuming a figure.

What the calculators do not do

They do not predict interest-rate changes, market returns or property prices, and they do not check your credit profile or represent any lender's decision. Results are estimates for planning and comparison. Read the full disclaimer, and if you find an error, please tell us.