§ Tools / Series 03 · Personal finance
SIP calculator
A deterministic recurring-investment projection: the systematic investment plan question for India, the monthly investment or DCA question everywhere else. For a contribution, an assumed return, and a tenure it returns the estimated corpus, and, unlike most free tools, it tells you exactly which compounding convention produced the number.
§ Market-linked, not a fixed-rate product
This projects periodic investing under an assumed return. Equity returns are not guaranteed and the smooth curve is not a forecast. For a fixed-rate bank product use the recurring deposit calculator; for one-time investing, the lump-sum calculator.
2
Rate conventions
3
Scenarios
5×5
Sensitivity grid
Goal-seek
Solve for contribution
v1
Methodology
§ Start with a preset
Three product-neutral starting points, adjust anything after.
Inputs
Independent units for the contribution and the lump sum · everything recomputes instantly.
Estimated corpus
$187,187.81
$500 monthly for 15 years at 9%. You invested $90,000.00.
Total earnings$97,188
Growth multiple2.08×
Real corpus · today's money$120,149
Total invested
$90,000
180 contributions
Total earnings
$97,188
51.9% of corpus
Absolute return
108.0%
earnings / invested
Average contribution
$500
flat
Fee drag · lifetime
−$3,434
0.2% annual expense
Periodic rate
0.7333%
per monthly · nominal
§ Invested vs earnings
How much of the corpus is your money vs market growth?
Y0Y2Y4Y6Y8Y10Y12Y14Y15
Total invested Estimated earnings
§ Scenarios
Bear, base, bull, 5% either side of 9%
Bear4.0%
$121,437
Base9.0%
$187,188
Bull14.0%
$300,449
§ Sensitivity
Return × tenure, the corpus across nearby assumptions
§ Goal-seek · solve the inverse
How much should you invest each month to hit a target corpus?
$
Required monthly contribution
$750
≈ 750 ones · reaches $280,782
§ Year-by-year schedule
The path, not just the endpoint
§ Formula trace
- contribution = 500 × ones = 500.00 USD / monthly
- periodicRate = R_net / 12 = 0.733333% (R_net after 0.2% fee)
- periods N = 15 × 12 = 180 · timing = beginning-of-period
- futureValue = 187187.81 (initial leg 0.00 + contribution leg 187187.81)
- totalInvested = 90000.00 · totalEarnings = 97187.81
- realFutureValue = FV / (1 + 3%)^15 = 120148.73
- feeDrag = FV(no fee) − FV = 3434.10 over 15y
§ Input audit
contributionused
contributionUnitused
currencyused
expectedReturnPctused
feePctused
frequencyused
inflationPctused
initialAmountdefaulted
initialUnitdefaulted
rateConventionused
returnVariancePctused
stepUpPctdefaulted
taxPctdefaulted
tenureYearsused
timingused
§ Warnings
- Equity returns are not guaranteed. The smooth projection is not a forecast; historical data is not a forecast either.
§ Golden references · locked in tests
Reference case: ₹1,000/month, 12%, 10 years, monthly. Four numbers pinned so the convention can't silently change.
Nominal · end
₹2,30,038.69
Nominal · beginning
₹2,32,339.08
Effective · end
₹2,21,930.04
Effective · beginning
₹2,24,035.89
The ~3.6% gap between nominal-end (₹2,30,038.69) and effective-end (₹2,21,930.04) on the same “12%” input is the whole point: it is which compounding convention you chose, nothing else.
§ Specialized siblings
§ Same engine, headlessly
The deterministic projection, sensitivity matrix, and goal-seek are reachable as stateless REST endpoints and MCP tools. Source-backed prefill, historical backtests, and account workbooks are unavailable in v1.
POST/api/v1/financial-calculators/sip/run
POST/api/v1/financial-calculators/sip/sensitivity
POST/api/v1/financial-calculators/sip/solve-contribution
GETSource-backed defaults · unavailable in v1
POSTHistorical backtest · unavailable in v1
MCP tools
calculate_sip_investment · solve_sip_monthly_contributionmethodology_version = financial-calculators.v1 · canonical = /en/tools/sip-calculator
§ FAQ
Four things worth knowing
Q01Why does “12%” give two different corpus numbers here?+
Because there are two ways to read a 12% return. Nominal APR (the SIP textbook convention) divides it by 12 to get a 1.0000% monthly rate. Effective annual treats 12% as the already-compounded yield, so the monthly rate is (1.12)^(1/12)−1 = 0.948879%. On a ₹1,000/month, 10-year, end-of-period SIP that is ₹2,30,038.69 vs ₹2,21,930.04, a ~3.6% gap on the same input. Most free calculators silently pick one and never tell you. This one makes it a toggle, and defaults to nominal APR for SIP parity.
Q02Beginning or end of period: does the toggle matter?+
Yes. Beginning-of-period (annuity due) means every contribution earns one extra period of growth, which is how most real SIPs behave. End-of-period means the last contribution earns nothing. On a 10-year monthly SIP the gap is about 1% of the final corpus, small per month, real over a decade. The default is beginning-of-period.
Q03How is the step-up SIP computed?+
With an iterative schedule, not a closed-form shortcut. Each year the contribution is multiplied by (1 + step-up rate), then per-period growth is applied. The same iterative path powers missed contributions and non-monthly frequencies, so the step-up number stays consistent rather than being bolted on.
Q04After inflation, fees, and tax, what is actually left?+
Those are three separate first-class outputs, not blanket disclaimers. Real future value deflates the corpus by inflation into today’s money. After-fee value nets an annual expense ratio out of the return. After-tax value applies an exit tax to positive gains only. You can mix and match them; each appears in the headline and the formula trace.