How to Use the SIP with Lumpsum Calculator
Enter the amount you can invest today as a lumpsum, the SIP you will run every month alongside it, your expected return, and the duration. The result separates the final corpus into the portion your lumpsum grew into and the portion your SIP built — with a stacked chart and a year-by-year split table, so you can see exactly what each rupee-stream contributes.
SIP with Lumpsum Calculator Formula
Corpus = L × (1+i)ⁿ + A × ((1+i)ⁿ − 1) ÷ i × (1+i)L= Initial lumpsum, invested on day oneA= Monthly SIP instalmenti, n= Monthly return (annual ÷ 12) and number of months
Example Calculation
₹5 lakh upfront plus ₹10,000/month at 12% for 15 years:
Lumpsum: 5,00,000 × (1.01)¹⁸⁰ ≈ ₹29.98L; SIP: 10,000 × ((1.01)¹⁸⁰ − 1) ÷ 0.01 × 1.01 ≈ ₹50.46L
Combined corpus ≈ ₹80.4 lakh on ₹23 lakh invested
Why the split matters, not just the total
Most calculators can tell you what ₹5 lakh plus ₹10,000 a month becomes. What they hide is the anatomy: which stream did the work? That split is not a curiosity — it drives real decisions. If the lumpsum share of your projected corpus is large, protecting that initial amount (fund quality, entry timing, asset allocation) matters more than optimising the SIP. If the SIP share dominates, consistency and step-ups matter more than anything you do with the opening balance. The stacked chart above shows the two streams separately for every year precisely so you can see which lever is yours.
The pattern is consistent: the lumpsum stream starts as the whole portfolio and shrinks in share every year as SIP instalments pile up — but each individual lumpsum rupee always outperforms each SIP rupee, because it was invested earliest. In the worked example, the ₹5 lakh (22% of total money in) still produces 37% of the final corpus after 15 years.
When adding a lumpsum beats raising the SIP — and when it doesn’t
People usually face this as a real fork: a ₹3 lakh bonus lands, and the choice is to invest it now or to raise the SIP by ₹25,000 for a year. The mathematics is unambiguous — money that exists should be invested when it exists. Deployed at once at 12%, the bonus starts compounding immediately; dripped in over 12 months, roughly half of it sits idle for months earning savings-account rates. Over 15 years the difference on ₹3 lakh is around ₹35,000–40,000 of lost growth, purely from the delay.
The honest exceptions: first, if a market fall during your entry year would make you panic-sell, staggering (or a formal STP) buys behavioural insurance at a known expected cost. Second, if the "lumpsum" does not exist yet — a bonus you expect, a maturing FD — then raising the SIP is not a worse choice, it is the only choice. The rule that survives every scenario: match the investment pattern to the cash-flow pattern, lumpsum for money you have, SIP for money you earn.
How an initial corpus bends the compounding curve
A pure SIP portfolio grows almost linearly for years — early on, each month’s instalment is large relative to the balance, so contributions dominate and compounding barely shows. An initial lumpsum changes the shape from day one: the portfolio starts on the compounding curve rather than the contribution line. Concretely, a plain ₹10,000 SIP at 12% takes about 7 years to cross ₹12.9 lakh; with ₹5 lakh upfront the combined portfolio crosses it in year 4. You effectively skip the flattest, most discouraging stretch of the journey.
This has a second-order behavioural benefit that the arithmetic understates: portfolios that visibly compound are portfolios people keep funding. The most common SIP failure is abandonment in the flat early years. An opening balance makes the growth visible earlier, and visible growth is what keeps instalments alive through the first market scare.
Reading your own numbers
- Lumpsum share above ~50% at the end: your outcome is dominated by market returns on the opening amount — diversify it properly and consider staggered entry if it is new money.
- SIP share above ~70%: your outcome is dominated by discipline — automate the SIP and add a yearly step-up (see the step-up SIP calculator) before optimising anything else.
- Compare the total against your goal in the goal SIP calculator; if there is a gap, an existing-savings entry there plays the same role as the lumpsum here.
- The year-by-year table shows the crossover year when SIP-built corpus overtakes the lumpsum stream — after that point, missed instalments cost more than entry-timing ever did.
Frequently Asked Questions
Can I start a SIP with an initial lumpsum amount?
Yes — most fund platforms let you make a one-time purchase into a scheme and register a SIP in the same scheme on the same day. They are two separate transactions into the same folio; this calculator projects both together and shows what each contributes.
Is it better to add a lumpsum or increase my SIP?
If the money already exists, invest it as a lumpsum — spreading it into a bigger SIP just delays deployment and, at a steadily positive return, ends lower. Increase the SIP when the money arrives monthly (from salary). The two answers differ because the question is really "when does the money exist?".
How much difference does the initial amount actually make?
A lot early, proportionally less over very long periods. In the worked example, ₹5L upfront is only 22% of the total invested but produces 37% of the corpus, because it compounds for the entire tenure while the average SIP rupee compounds for only half of it.
Should the lumpsum go into the same fund as the SIP?
The maths here is fund-agnostic. In practice many investors park a large lumpsum in a liquid fund and STP it into the equity fund over 6–12 months to reduce entry-timing risk — the projection is then slightly lower but the worst case improves.
Why does this show a different number from the plain SIP calculator?
It includes the lumpsum’s growth. Set the initial amount to zero and the result matches the SIP calculator to the rupee — both use the same start-of-month, monthly-compounding convention.
Assumptions & Methodology
- The lumpsum is invested on day one and both components compound monthly at the same constant rate (annual ÷ 12), matching the SIP calculator’s convention — so ₹0 lumpsum here equals the plain SIP calculator exactly.
- SIP instalments are invested at the start of each month (annuity-due).
- Taxes, expense ratios and exit loads are not deducted; real market returns vary year to year.
Sources
All calculations run in your browser and are provided for information only — they are not investment, tax or legal advice. Verify current rates and rules with the official source above before acting.