Guide and glossary

How this retirement calculator thinks.

This page explains the mental model behind the calculator, the meaning of every major term, and the risks you should stress-test before trusting any long-term projection.

Not financial advice

RetireFlow is a planning simulator. It does not recommend investments, promote financial products, or tell you what to buy, sell, hold, redeem, or avoid.

Real returns, taxes, inflation, product costs, and withdrawal behavior can differ materially from a simple browser model.

Financial Freedom vs True Retirement

ConceptMeaning in this calculatorDecision it helps with
Financial freedom / FI ageThe age when work becomes optional because your corpus can start funding monthly expenses through SWP.How much corpus you may need before reducing dependence on salary.
True retirement ageThe age when you want to stop taking market-heavy decisions and move remaining corpus to FD/debt-style income.How long the SWP bridge must last before the safer phase begins.
Plan until ageThe stress-test age until which money should last.Longevity risk: whether the plan survives a longer life.

The 3-Phase Mental Model

Phase 1 · Build

SIP + Lumpsum

You invest monthly, increase SIP annually, and let compounding work. This phase assumes you can tolerate volatility because income still comes from work.

Phase 2 · Stabilize

FI / SWP bridge

The SIP corpus becomes an income engine. You withdraw monthly, increase withdrawals with inflation, and keep the remaining corpus invested.

Phase 3 · Sleep

FD / Low-risk retirement

At true retirement, the calculator shifts the remaining corpus to a lower-risk return assumption so the plan prioritizes simplicity and fewer decisions.

Every Input Term

Current ageYour age today. It sets how many years are available before FI age.
Financial independence ageThe age where SIP stops in the model and the SWP income phase begins.
True retirement ageThe age where the model shifts from SWP to a lower-risk FD/debt-style phase.
Plan until ageThe age until which the calculator checks corpus survival.
Monthly expense todayYour current living cost. The calculator inflates it until FI age and true-retirement age.
Retirement lifestyleA multiplier on current expenses: monk means lower spend, current lifestyle means same spend, and king means higher spend.
Saving styleA quick preset for return assumptions. You can still edit each return number manually.
InflationThe annual rise in living cost. A 6% inflation assumption means Rs 50,000/month becomes Rs 53,000/month after one year.
Monthly SIPThe monthly investment you start with during the accumulation phase.
Annual SIP step-upHow much you increase SIP every year. For example, 10% on Rs 5,000 means next year's SIP increases by Rs 500/month.
Expected SIP returnThe annual return assumption during the aggressive phase. The calculator converts this into an effective monthly rate.
Existing corpus / lumpsumMoney already invested today. It grows separately until FI age using the lumpsum return assumption.
Lumpsum returnThe annual growth assumption for existing corpus before FI age.
Tax dragA simplified return haircut for taxes or product costs. It reduces effective return before projection.
SWP returnThe expected return on your corpus while you are withdrawing monthly income after FI age.
SWP increaseThe annual increase in monthly withdrawals. Usually this should match inflation unless you plan lifestyle changes.
Emergency bufferExtra months of expenses added to required FI corpus so the plan is less fragile.
FD / low-risk returnThe return assumption after true retirement. This is intentionally more conservative than aggressive equity-style growth.
FD compoundingHow often FD/debt interest is assumed to compound: monthly, quarterly, half-yearly, or yearly.
FD taxA simplified haircut on FD interest to represent taxes or other costs.
FD modeDrawdown allowed spends principal when needed. Interest-only checks whether interest alone covers expenses.

Every Output Term

Projected corpus at FIWhat your SIP plus existing corpus may become at FI age.
Required corpus at FIThe corpus needed to fund the SWP bridge, FD phase, and emergency buffer.
Surplus / shortfallPositive means projected FI corpus exceeds the model requirement. Negative means current assumptions are insufficient.
FI monthly withdrawalToday's lifestyle-adjusted monthly expense inflated to FI age.
FD principal at true retirementThe remaining corpus after SWP that moves into the FD/debt phase.
Monthly SIP neededThe approximate starting SIP required to hit the same plan target under current assumptions.
Corpus pathThe year-by-year closing corpus across SIP, SWP, and FD phases.
Annual cashflowPositive values are investments. Negative values are withdrawals or expenses.

Formula Words

TermPlain-language meaning
CorpusThe pool of money being built or spent from.
CAGR / annual returnThe assumed yearly growth rate before it is converted into monthly math.
Monthly rateThe effective monthly growth rate derived from the annual return.
CompoundingReturns earning returns over time.
DrawdownUsing part of the principal when interest or returns are not enough.
Reverse simulationWorking backward from the FD principal needed at true retirement to estimate required FI corpus.

Risks to Stress-Test

Market riskSIP and SWP returns are assumptions, not guarantees.
Sequence-of-returns riskLosses early in the SWP phase hurt more because you are withdrawing while the portfolio is down.
Inflation riskIf actual inflation is higher than assumed, monthly withdrawal needs rise faster than the model expects.
Longevity riskLiving longer than the selected plan age means the corpus must last longer than shown.
Tax and product-cost riskCapital gains tax, exit load, expense ratio, FD tax, and platform costs can reduce real returns.
FD / bank concentration riskVery large fixed deposit allocations should not be treated as risk-free.

About the Creator

RetireFlow was created by Pranshu Basak. His public portfolio describes him as a full-stack developer and CRM architect focused on Creatio CRM, API integrations, business process automation, reliable backend systems, practical developer workflows, cloud-native deployment, and AI-assisted product engineering.

Basak Speaks is Pranshu's linked blog property for technical writing and practical guides.

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