SIP Calculator — what this tool does differently
A SIP calculator estimates what a Systematic Investment Plan — a fixed amount invested at regular intervals, usually monthly — could grow into over time. Nearly every SIP calculator online asks for three numbers (monthly amount, expected return, years) and shows you one big, flattering total.
That number is misleading in two specific ways, and this calculator fixes both:
- It ignores fund fees. Most calculators openly state they exclude the expense ratio. But a 1% annual fee compounds against you for the entire holding period. On a 10-year SIP it can quietly eat tens of thousands.
- It ignores inflation. A headline figure decades out sounds enormous, but what matters is what it buys. This tool shows the inflation-adjusted real value alongside the nominal one.
It also handles step-up SIPs, an initial lumpsum combined with monthly contributions, a reverse goal planner, a year-by-year table, CSV export, and four currencies — all in one page, entirely in your browser.
How this compares to a typical SIP calculator
| Feature | Typical SIP calculator | This calculator |
|---|
| SIP maturity value | Yes | Yes |
| Lumpsum mode | Usually a separate page | Built-in tab |
| Step-up / top-up SIP | Usually a separate page | Built-in tab |
| Lumpsum + SIP combined | No | Yes |
| Expense ratio / fee drag | Explicitly excluded | Modelled & quantified |
| Inflation-adjusted real value | No | Yes, side by side |
| Year-by-year breakdown | Rarely | Full table + CSV |
| Growth chart over time | Donut only | Growth curve + donut |
| Reverse goal planner | No | Yes |
| Multi-currency (₹ € $ £) | No | Yes, with regional presets |
| Shareable deep link | No | Yes |
| Account required | Often, to invest | Never — nothing to sell you |
The SIP formula — and the mistake most calculators make
The standard SIP maturity formula is:
M = P × ( [ (1 + i)n − 1 ] ÷ i ) × (1 + i)
Where M is the maturity amount, P is the amount invested each month, n is the number of contributions, and i is the periodic (monthly) rate of return.
The trap is in i. It is tempting to take a 12% annual return and call it 1% per month. That is wrong, because returns compound. Compounding 1% monthly for a year gives 12.68%, not 12%. The correct conversion is:
i = (1 + annual return)1/12 − 1
For 12% per year that gives 0.9489% per month, not 1%. This calculator uses the effective monthly rate, so a 12% input genuinely means 12% a year. Worked example: ₹1,000/month for 12 months at 12% gives ₹12,766, on ₹12,000 invested.
Where the trailing (1 + i) comes from
That final term makes it an annuity due — it assumes each contribution is made at the start of the month, so it earns a full month of return. This matches how a real SIP debit works. Calculators that omit it assume end-of-month investing and will show slightly lower figures.
Step-up SIP — the single biggest lever
A step-up SIP (also called a top-up SIP) raises your monthly contribution by a set percentage each year, typically 5–10%, roughly tracking salary growth. Because the increases compound alongside your returns, the effect is far larger than it sounds.
Take ₹5,000/month for 10 years at 12%:
- Flat SIP: ₹6,00,000 invested → about ₹11.2 lakh
- With 10% annual step-up: ₹9,56,000 invested → about ₹16.3 lakh
That is roughly 46% more, from increases you barely feel because they arrive gradually and in step with your income. Over 20–30 years the divergence becomes dramatic. Use the Step-Up SIP tab to model your own numbers.
What the expense ratio really costs you
The expense ratio is the annual fee your fund charges, deducted from the fund's value before you ever see a return. It is quoted as a small number, which is exactly why it is underestimated.
₹5,000/month for 10 years at a 12% gross return:
- Zero fees: about ₹11.2 lakh
- 1% expense ratio: about ₹10.6 lakh — roughly ₹58,000 gone
Over 20–30 years, the gap grows into a very large fraction of your returns. This is the core argument for low-cost index funds and ETFs (typically 0.05–0.30%) over active funds (often 1–2%). Toggle the expense ratio on and off in this calculator to see the difference on your own plan — the figure it shows is money that leaves your pocket regardless of how the fund performs.
Inflation — what your corpus is actually worth
Nominal returns flatter long horizons. The real question is purchasing power:
Real value = Nominal value ÷ (1 + inflation)years
At 6% inflation, ₹11.2 lakh in 10 years has the buying power of roughly ₹6.3 lakh today — a headline number that is almost half illusion. This does not mean investing failed; it means the target should be set in real terms. Turn on the inflation toggle to see both figures at once, and plan against the one that buys groceries.
SIP vs lumpsum — which actually wins?
Mathematically, a lumpsum invested at the start beats an equivalent SIP over the same period, because every unit of currency is invested for longer. That is arithmetic, not opinion.
But the comparison assumes you already hold the full amount and that markets rise smoothly. In practice a SIP wins on grounds that matter more:
- It matches how people actually earn — monthly.
- It removes the need to time the market, which almost nobody does well.
- It averages your purchase price across highs and lows, which softens the emotional damage of a crash right after you invest.
The realistic middle ground is both: invest a lumpsum you already have, then keep contributing monthly. This calculator models that combination directly — enter an initial lumpsum on the SIP tab.
Using this outside India — Europe, US and UK
"SIP" is Indian terminology, but the mechanism is universal — a recurring investment into a fund. Switch currency with the region buttons and the same maths applies:
- 🇮🇳 India — SIP into mutual funds. Amounts format with the lakh/crore convention.
- 🇪🇺 Europe — monthly ETF savings plan, known as a Sparplan in Germany and Austria, plan d'investissement programmé in France.
- 🇺🇸 US — dollar-cost averaging: recurring 401(k), IRA or taxable brokerage contributions.
- 🇬🇧 UK — monthly contributions into a Stocks & Shares ISA or SIPP.
Switching region also loads sensible default return, inflation and expense-ratio assumptions for that market, since a 12% expected return is a common Indian equity assumption but an aggressive one for developed-market portfolios.
How to use this SIP calculator
- 1. Pick a mode — SIP for regular monthly investing, Lumpsum for a one-time amount, Step-Up SIP for contributions that rise each year.
- 2. Choose your region to set currency and sensible defaults.
- 3. Enter your plan — monthly amount, expected return, and time period. Add an initial lumpsum if you have one.
- 4. Set the real-world adjustments — your fund's expense ratio and an inflation assumption.
- 5. Read the results — invested vs growth vs total, plus real value and fee drag.
- 6. Work backwards with the goal planner if you have a target number in mind.
- 7. Export or share — download the year table as CSV, or copy a link that reopens your exact scenario.
Deep links — URL parameters
The address bar stays in sync as you edit, so any scenario is shareable and bookmarkable. You can also construct links by hand:
?amount=5000&rate=12&years=10 — a ₹5,000 monthly SIP at 12% for 10 years.
Optional: mode (sip|lumpsum|stepup), lump (initial lumpsum), stepup (annual increase %), er (expense ratio %), infl (inflation %), currency (INR, EUR, USD, GBP), goal (target amount).
Privacy — nothing leaves your browser
Every calculation runs locally in JavaScript. Your contribution amounts, targets and assumptions are never transmitted, stored or logged. There is no account, no ads, no tracking of your inputs, and no product being sold to you at the end — which is not true of most SIP calculators, which exist to open brokerage accounts. The page works offline once loaded.