How the calculations work

Calculations run in your browser using JavaScript floating-point numbers. Intermediate amounts retain their precision; displayed rupee amounts round to the nearest rupee using Indian grouping. Adding rounded table rows can differ slightly from the displayed total.

Modeled cash amounts accept whole rupees; PPF annual deposits use permitted ₹50 increments. Percentage inputs accept 0.01 percentage points. Ages and periods remain whole numbers. Values are clamped to the displayed ranges and adjusted only to these supported increments. Related ages and loan prepayment bounds adjust together; invalid shared inputs fall back to defaults.

The investment is made at the start of each month. The monthly return i is the expected annual percentage divided by 12 and 100; n is the number of months and P is the monthly contribution.

FV = P × ((1 + i)ⁿ − 1) ÷ i × (1 + i)

At a zero return the value is the sum of contributions. A step-up increases the monthly contribution once each year: P × (1 + step-up/100)ʸ, with y starting at 0. The monthly simulation follows the same deposit timing. The gain over a flat SIP includes extra contributions, not just extra investment returns. Returns are constant assumptions; market volatility, tax and fees are excluded. The annual input is nominal: 12% means 1% monthly, about 12.68% effective annual growth. An effective-annual return convention produces a different projection.

The loan has a constant interest rate and monthly reducing-balance repayments. P is the principal, r is the annual percentage divided by 12 and 100, and n is the tenure in months. Home, car and personal loan pages use this same engine with different input ranges.

EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)

Each month, interest equals the opening balance × r; the rest of the instalment repays principal. At zero interest EMI is P ÷ n, and the last instalment clears the remaining balance. One-time prepayment follows the selected EMI; yearly prepayment follows every 12th EMI. Coinciding extras combine and are capped at the balance. Reduce tenure keeps EMI; reduce EMI recalculates it over the original remaining months. Savings compare the same loan without extras. Rate resets, disbursement delays, fees, insurance, penalties and tax benefits are excluded.

One annual deposit is assumed to be available by the close of 5 April and earns a full year of interest. The annual deposit is capped at ₹1,50,000. Each year adds the deposit before compounding.

Closing balance = (opening balance + annual deposit) × (1 + rate/100)

Actual PPF interest depends on the lowest eligible monthly balance from the close of the fifth day to month-end and is credited annually. Depositing later or in instalments changes interest. This model holds the selected rate constant and keeps annual deposits going through the selected period; withdrawals, loans, missed deposits and extension choices are excluded.

The editable default is 7.1%. It is a projection assumption, not a guarantee of future rates. Check the latest government notification before using it for a decision.

Today’s monthly expenses grow with annual inflation until retirement. The corpus is the present value at retirement of monthly spending, paid at the start of each month, through your selected planning age.

Monthly real return = ((1 + post-return/100) ÷ (1 + inflation/100))^(1/12) − 1

A monthly annuity-due present value uses that real return; when it is zero, corpus is monthly expenses × retirement months. Existing savings grow annually at the pre-retirement return. The gap is max(0, corpus − future value of savings). The required SIP solves the start-of-month SIP formula for that gap, using pre-retirement return ÷ 12. Annual compounding of existing savings differs from monthly compounding of new SIPs. No pension, taxes, fees, emergency reserve or inheritance target is included.

The corpus earns the assumed annual return divided by 12 and 100 each month, then pays the fixed withdrawal at month-end.

Closing balance = opening balance × (1 + monthly return) − withdrawal

The actual withdrawal is capped at the available balance. A final partial withdrawal is included in total withdrawals, and the simulation stops at depletion or your selected period. Fund duration counts the partial withdrawal month. A positive ending balance says only that the fund lasted through the simulated period. Constant returns exclude market volatility, tax, fees and changes in spending.

This model covers resident individuals with ordinary salary income only. It computes both regimes using the configured Income-tax Act, 2025 rules as amended by Finance Act, 2026.

Tax rules checked 2026-11-14. This is a salary-only estimate for resident individuals; verify your own filing position.

Salary standard deduction is ₹50,000 in the old regime and ₹75,000 in the new regime, capped at salary. Other eligible deductions apply only to the old regime and cannot reduce taxable income below zero.

Old-regime rebate is up to ₹12,500 at taxable income up to ₹5,00,000. New-regime rebate is up to ₹60,000 at taxable income up to ₹12,00,000, with marginal relief just above that limit. This is Section 156 of the 2025 Act, the successor to Section 87A.

Each rate applies only to income in that band. Surcharge applies above the configured taxable-income thresholds: 10% above ₹50 lakh, then 15% above ₹1 crore and 25% above ₹2 crore; the old regime also has 37% above ₹5 crore. The current salary input is capped at ₹1 crore. Applicable surcharge marginal relief is deducted before 4% health and education cess.

Capital gains, business income, special-rate income, agricultural income effects and non-resident rules are excluded. Taxable income and final tax retain full precision until display; statutory filing rounding and individual deduction eligibility require separate checking. Age affects the old-regime exemption only.

For SIP, PPF and SWP, today’s-money value is nominal ending value ÷ (1 + inflation/100)ʸᵉᵃʳˢ. This display does not change contributions, withdrawals or nominal balances.

Inflation is a constant scenario assumption. Different goods and households experience different price changes; these projections do not predict your actual future cost of living.