Clear inputs. Explicit assumptions.

SiP Money · Calculator methods

The calculation methods behind our SIP, income runway and SWP tools. Each is a simple scenario controlled by the reader.

Method version 1.1.0 · 11 October 2026

SIP calculator

Example inputs: Starting monthly investment 10000 INR · Investment period 10 years · Assumed annual return 8% · Annual contribution increase 0%.

The contribution is added at the start of each month. That month’s assumed growth is then applied to the resulting balance.

The monthly rate is derived from an effective annual rate. Dividing the annual percentage by 12 would use a different compounding convention.

If you enter a contribution increase, the first increase occurs in month 13 and then every 12 months. The limit on the starting monthly investment applies to the initial input; stepped contributions can become larger in later years.

The calculation retains unrounded values. Displayed amounts are rounded to rupees; the CSV retains two decimal places. The chart connects exact year-end values from the monthly schedule.

The 0–20% input range is a scenario-control range, not a statement about the possible limits of actual market returns. This tool does not model variable returns or recommend a scheme.

Calculation convention

monthly rate = (1 + annual return / 100)^(1/12) − 1 closing balance = (opening balance + contribution) × (1 + monthly rate) contribution in month m = starting monthly amount × (1 + annual increase / 100)^floor((m − 1) / 12)

What this tool is for

These are user-controlled educational scenarios. They do not choose a product, assess suitability, recommend an allocation, or determine whether a plan is adequate. The chosen rates and example inputs are illustrations, not forecasts.

Privacy of the calculator

This calculator runs in your browser. Its code does not send financial inputs or results to a server, use cookies, load analytics, or store your entries. An optional message tells the containing page only the tool name, version and required display height. The surrounding website has its own privacy practices.

AMFI: what an SIP means (opens in a new tab). This source explains the financial concept; SiP Money defines the calculation conventions above.

Method version 1.1.0 · 11 October 2026.

Income runway

Example inputs: Cash set aside 300000 INR · Monthly essentials 50000 INR · Ongoing monthly income 20000 INR.

The tool subtracts ongoing monthly income from essential monthly spending. When spending exceeds income, cash set aside is divided by that shortfall.

A result such as 10.5 months is a simple proportional estimate. Actual bill dates, irregular expenses and changes in income can alter when cash is needed.

If income covers the entered essentials, the tool reports no monthly gap. It does not describe savings as lasting forever or claim that all future costs are covered.

No interest or investment return is assumed. The calculation excludes inflation, tax changes, new costs and unexpected large expenses.

Calculation convention

monthly shortfall = max(monthly essentials − ongoing monthly income, 0) months of cover = cash set aside ÷ monthly shortfall (only if the shortfall is positive)

What this tool is for

Privacy of the calculator

NCFE: emergency funds and financial planning (opens in a new tab). This source explains the financial concept; SiP Money defines the calculation conventions above.

Method version 1.1.0 · 11 October 2026.

SWP calculator

Example inputs: Starting corpus 5000000 INR · Starting monthly withdrawal 30000 INR · Scenario length 20 years · Assumed annual return 6% · Annual withdrawal increase 0%.

Withdrawals occur at the start of each month. The first request is made against the starting corpus, before any assumed growth. Growth or loss then applies to the remaining capital.

The actual withdrawal cannot exceed the available corpus. A final payment can be partial. Once there is no capital, no further cash is generated by this model; unmet requests are recorded separately and the balance never becomes negative.

An optional annual increase changes the amount requested beginning in month 13 and every 12 months thereafter. This is an assumed withdrawal increase; it is not a prediction of inflation. The initial withdrawal limit does not cap later increased requests.

The tool separates requested withdrawals, actual cash withdrawn, unmet withdrawals, hypothetical net growth or loss, and capital remaining. A corpus that lasts through the selected horizon is not a conclusion about what happens afterwards.

The chart uses exact month-by-month balances and cumulative withdrawals. The table groups those monthly values by year. Calculations retain unrounded values; funding and depletion labels treat amounts below half a paise as numerical zero. No money is created by that tolerance.

A constant return path does not capture sequence-of-returns risk: the timing of market gains and losses matters when withdrawals are being made. Taxes, fund costs, transaction charges and irregular extra expenses are excluded.

Calculation convention

monthly rate = (1 + annual return / 100)^(1/12) − 1 requested withdrawal in month m = initial monthly withdrawal × (1 + annual increase / 100)^floor((m − 1) / 12) actual withdrawal = min(requested withdrawal, opening corpus) closing corpus = max(opening corpus − actual withdrawal, 0) × (1 + monthly rate) unmet withdrawal = requested withdrawal − actual withdrawal

What this tool is for

Privacy of the calculator

AMFI: how an SWP works (opens in a new tab). This source explains the financial concept; SiP Money defines the calculation conventions above.

Method version 1.1.0 · 11 October 2026.

EMI and tenure comparison

The loan model uses a fixed nominal annual interest rate divided by 12, monthly payments at month-end and no fees, tax, insurance, prepayments or rate resets. For principal P, monthly rate r and n months, EMI = P × r / (1 − (1+r)−n). At zero interest EMI = P/n. Each month charges interest on the opening balance, then applies the payment. The last payment settles the amount owed, including any floating-point residual. Displayed rupees are rounded; calculations retain precision. A second tenure holds principal and rate constant to reveal the payment/interest trade-off.

This EMI is not an APR quotation. RBI’s credit disclosures distinguish interest and other costs; compare the lender’s actual Key Facts Statement and schedule. Open EMI comparison

Inflation and purchasing power

Future cost = current cost × (1+i)y. Purchasing power of a fixed future rupee amount = that amount / (1+i)y. The illustrative stress case adds two percentage points to the chosen inflation rate; it is not a probability or forecast. Annual rows run from year zero to the selected year. Open inflation calculator

Goal funding

The future target is today’s goal × (1+inflation)years. Existing savings grow at the selected hypothetical effective annual return. Monthly rate = (1+return)1/12−1. The remaining gap is funded by equal month-start contributions followed by growth, matching our SIP convention. At zero return, monthly contribution = gap / number of months. Negative gaps become zero; a positive result is rounded up to a whole rupee. The comparison case reduces the chosen return by two percentage points, with a floor of zero. It is an illustrative sensitivity, not a minimum expected return. No taxes, charges, step-ups or changing rates are included. Open goal calculator

Primary context for the new tools

SEBI: inflation illustration · SEBI: financial goal planning · RBI: Key Facts Statement and loan-cost disclosure. Calculation conventions and independent numerical checks updated 18 October 2026. Model agreement is not a forecast or professional suitability review.