SIP vs Lumpsum: The Same ₹12 Lakh Ends ₹14 Lakh Apart, and When Each One Wins

Invest ₹12 lakh at 12% for ten years and the lumpsum calculator says ₹37,27,018. Invest the same ₹12 lakh as a ₹10,000-a-month SIP for the same ten years at the same 12% and the SIP calculator says ₹23,23,391. People see a ₹14 lakh gap and conclude that lumpsum is the better product. It is, in exactly one situation: when you already have the ₹12 lakh. That situation is the only thing the comparison describes, and it is not the situation most people are in.

The worked comparison

Same total invested, same 12% a year, the lumpsum on day one versus ₹10,000 on the first of every month:

Years	Total invested	SIP grows to	Lumpsum grows to	Gap
1	₹1,20,000	₹1,28,093	₹1,34,400	₹6,307
5	₹6,00,000	₹8,24,864	₹10,57,405	₹2,32,541
10	₹12,00,000	₹23,23,391	₹37,27,018	₹14,03,627
15	₹18,00,000	₹50,45,760	₹98,52,418	₹48,06,658
20	₹24,00,000	₹99,91,479	₹2,31,51,103	₹1,31,59,624

Nothing about the SIP is inefficient here. In the ten-year row the first ₹10,000 compounds for 120 months and the last ₹10,000 for one month, so on average the SIP has roughly half the money at work that the lumpsum has. Half the money at work, for the same time, at the same rate, earns less. That is the whole explanation, and it is the same arithmetic that makes an FD out-earn an RD in the FD vs RD comparison.

The gap widens with the rate, because more compounding is being forgone:

Expected return	₹10,000 SIP for 10 years	₹12 lakh lumpsum for 10 years
8%	₹18,41,657	₹25,90,710
10%	₹20,65,520	₹31,12,491
12%	₹23,23,391	₹37,27,018
15%	₹27,86,573	₹48,54,669

To match the ₹12 lakh lumpsum over ten years at 12%, the SIP would have to be ₹16,041 a month, ₹19.2 lakh in total.

The question that actually decides it

Do you have the money today?

• You do not have it, but you can spare ₹10,000 a month: SIP, and the comparison above is irrelevant to you. Your alternative is not a lumpsum; it is ₹10,000 a month sitting in a savings account at 3% while you wait to accumulate something worth investing. The SIP is how the lumpsum gets built.
• You do have it, from a bonus, a maturing FD or a property sale: lumpsum has the higher expected outcome, for the reason the table shows. The only argument for spreading it out is the one in the next section, and it is a real argument, not a rounding error.

When SIP wins even though you have the money

The tables assume the fund rises smoothly at 12% a year. Markets do not. Take ₹1,20,000 into a fund whose NAV goes 100, 80, 90, 100 over four quarters and ends the year at 110:

	Lumpsum at NAV 100	Four SIPs of ₹30,000 at 100, 80, 90, 100
Units bought	1,200	1,308.3
Average cost per unit	₹100	₹92
Value at NAV 110	₹1,32,000	₹1,43,917

The SIP bought more units while the price was down, which is all rupee-cost averaging means. Now run the same year with the NAV going 100, 105, 110, 115 and ending at 120: the lumpsum is worth ₹1,44,000 and the SIP ₹1,34,317, because every later instalment paid more per unit than the first.

So the rule is honest and symmetrical. SIP wins when the months after you start are worse than the start; lumpsum wins when they are better. Over long periods equity markets rise more often than they fall, which is why lumpsum wins more often. But when lumpsum loses, it loses at the worst possible moment: money put into the Sensex at its January 2008 peak was still under water in the middle of 2010, while a SIP started the same month was buying at 40% off within a year. Lumpsum has the higher average; SIP has the smaller regret.

The middle path: STP

If you have a lumpsum and the market makes you nervous, you do not have to choose. A systematic transfer plan parks the whole amount in a liquid or overnight fund of the same fund house and moves a fixed sum into the equity fund every month, typically over six to twelve months. The parked portion earns roughly 6% to 7% instead of the 3% a savings account pays, and the equity entry is averaged the same way a SIP averages it. Two things to know: each transfer is a redemption from the debt fund, so the small gain on it is taxable at your slab in the year it happens, and an STP spread over three years is no longer averaging, it is just delay.

Where SIP and lumpsum differ on tax and exits

Each SIP instalment is a separate purchase with its own holding period. For an equity fund, units held over twelve months are long-term and gains above ₹1.25 lakh a year are taxed at 12.5%; units sold inside twelve months are short-term and taxed at 20%. Redeem a three-year SIP in full and the last eleven instalments are still short-term, and the fund's exit load, usually 1% within a year, applies to those units too. Redemptions go out first-in, first-out, which helps: the oldest, long-term units leave first. A lumpsum has a single date, so it crosses the twelve-month line all at once.

What people get wrong

• Comparing unequal money. A ₹10,000 SIP and a ₹12 lakh lumpsum in the same year are not the same investment; only the ten-year totals match.
• Stopping the SIP when the market falls. The falling months are the ones where the SIP does its job. Pausing it converts the SIP into a badly timed lumpsum.
• Holding a lumpsum in savings while "doing SIP" out of it. ₹12 lakh earning 3% for years while ₹10,000 a month trickles out is the worst of both. Use an STP.
• Never raising the instalment. A SIP that grows with your salary closes much of the gap in the first table; the step-up SIP guide and the step-up SIP calculator show by how much.
• Measuring SIP returns with CAGR. CAGR assumes one date in and one date out. A SIP has 120 dates in; its return is an XIRR, and the XIRR calculator is the only fair way to compare it against a lumpsum's CAGR. CAGR vs XIRR explains why the two numbers differ.

For the mechanics of the SIP itself, including how the calculator's formula works, see how the SIP calculator plans mutual fund investments.

FAQ

Is SIP better than lumpsum?

If you already have the money, a lumpsum has the higher expected value because every rupee compounds from day one; a SIP of the same total over the same period ends lower in a steadily rising market. If you do not have the money, SIP is not a worse option, it is the only one. SIP wins outright when the market falls after you start.

Can I convert a lumpsum into a SIP?

Yes, through a systematic transfer plan: park the amount in a liquid fund and move a fixed sum into the equity fund each month, usually over six to twelve months. It averages the entry and keeps the waiting money earning more than a savings account.

How do I compare the return on a SIP with a lumpsum?

Use XIRR for the SIP, because it has many purchase dates, and CAGR for the lumpsum, which has one. Comparing a SIP's simple return against a lumpsum's CAGR understates the SIP every time.