Key takeaways
- SIP and lump sum describe when cash is available, not two magical return engines.
- Projected SIP “returns” in a calculator are the rate you typed, compounded on a contribution schedule — not a guarantee.
- Invested amount and estimated gains are separate columns. Do not read the gain column as money already earned.
- Step-up SIPs change the contribution path; they do not remove market risk.
Most salaried investors in India do not face a monthly choice between “SIP or lump sum.” Salary arrives monthly. A SIP is simply a standing instruction that matches that cash flow. A lump sum becomes a real choice when a bonus, maturity proceeds or a sale puts a large amount in the bank at once.
Finaura already has a longer essay on the arithmetic of investing a large sum immediately versus staggering it (SIP or lumpsum: what the maths actually says). This page is the vocabulary layer: what each word means, what a calculator is doing, and what it is not promising.
What a SIP is
A systematic investment plan is a repeated purchase, usually monthly, of a fund or other instrument. You choose an amount and a date. Units are allotted at that day’s price. There is no contracted return. The SIP calculator asks you for an expected annual rate so it can illustrate a future value. That rate is an assumption. Markets do not owe it to you.
What a lump sum is
A lump-sum investment is a single contribution that then compounds (or falls) as a whole. The lumpsum calculator uses the same kind of assumed rate as the SIP tool, on a different cash-flow shape. Comparing a ₹10,000 SIP for 15 years with a ₹18 lakh lump sum at 12% is comparing two different amounts of capital at work for different lengths of time. Align the money and the horizon before you declare a winner.
Invested amount versus estimated returns
Every honest projection splits two piles: what you put in, and what the assumed rate added. If you stop the SIP, the “estimated returns” column was never cash in your pocket. If the actual rate is lower, that column shrinks. If it is negative for a stretch, the corpus can sit below the invested amount. Calculators that hide this split make SIP look like a deposit.
Why the assumed return dominates the picture
Over 20 years, the difference between a 10% illustration and a 12% illustration is not a rounding error. Duration works the same way: year 20 does more heavy lifting than year 3. Use the calculator to see sensitivity — try two rates and two durations — rather than to pick a single “target corpus” you then treat as a promise.
Step-up SIP is still a SIP
A step-up SIP raises the instalment on a schedule, often annually, to track a rising salary. It changes how much you contribute, not the fact that each instalment buys at an unknown future price. See step-up SIP explained and the step-up calculator.
Try it yourselfProject a level SIPMonthly amount, assumed rate, duration — with invested amount separated from illustrated gains.A practical way to use both tools
- If the money is still in future salaries, a SIP illustration is the matching sketch.
- If the money is in the bank today, a lumpsum illustration (and the behavioural question of whether you would panic after a drop) is the matching sketch.
- If you will raise contributions with salary, use the step-up tool rather than pretending a level SIP captures that plan.
Limitations
These calculators ignore expense ratios, taxes on gains, exit loads and the sequence of actual yearly returns. A smooth 12% line is a teaching device. Real NAVs jump. Do not fund a near-term expense with a long-horizon equity illustration.