SIP vs Lumpsum Calculator

SIP vs. Lumpsum — Framing the Right Question

The SIP vs. lumpsum debate comes down to one thing: timing risk. Lumpsum investing concentrates all your purchase at a single point in time. If you invest at a market peak, you sit through years of underperformance waiting to recover. SIP spreads that timing risk across months or years, averaging your purchase price.

Mathematically, if markets go straight up, lumpsum always wins. You put all the money in at the start and it compounds for the longest period. In a rising market, SIP dilutes your early gains by investing later at higher prices.

In volatile markets — which is most markets — SIP often wins on a risk-adjusted basis because you benefit when prices dip mid-investment. The honest answer: for most people with a salary, SIP is the default choice because lumpsum requires having a large corpus and the confidence to deploy it at the right time. Both conditions are hard to meet simultaneously.

Rupee Cost Averaging — The Mathematics

When you invest a fixed rupee amount each month, you buy more units when the NAV is low and fewer when it is high. Over time, your average cost per unit ends up lower than the simple average of the NAVs during that period.

Rupee Cost Averaging — Continued Analysis

Total invested: ₹60,000. Total units: 1,310.9. Average cost per unit: ₹60,000 ÷ 1,310.9 = ₹45.77. Simple average of NAVs: (50+45+40+42+48+52)/6 = ₹46.17. Your SIP average (₹45.77) is lower than the simple NAV average — that is rupee cost averaging working as intended.

The effect is most pronounced during volatile markets with large dips. In a market that falls 20% and then recovers, the SIP investor who bought heavily during the dip ends up with a much better average than the lumpsum investor who went in before the fall.

When Lumpsum Makes Sense

Lumpsum is clearly better when you receive a large corpus at once — inheritance, property sale, retirement corpus, bonus — and markets are in a clear downtrend or at significant correction levels. Deploying systematically when Nifty P/E is below 18-20x historically produced better lumpsum outcomes than waiting.

STP (Systematic Transfer Plan) is the middle ground. You park the lumpsum in a liquid or overnight fund (earning 6-7% annual returns), then transfer a fixed amount to the equity fund monthly over 6-12 months. You earn money on the parked corpus while averaging into equity. This is standard practice for HNI investors managing large windfalls.

Historical data on Nifty: lumpsum in January 2008 (pre-crash) took until 2013 to recover. SIP over the same 2008-2013 period delivered 12-14% CAGR because of the heavy buying during the 2008-2009 crash. That is the SIP advantage in action.