This post shows a way to estimate the final corpus for a SIP

📚 Table of Contents

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• Introduction
• A better way
• The “best” way
• Summary of the three approaches
• Using a SIP calculator that does this
• Caveat on these calculations
• A note on the effects of inflation
• Why you need to invest as per your goals
• Further reading

Introduction

A common question amongst investors is what corpus value they will reach if they start investing in mutual funds via SIP form.

Before that, read this article to know more about SIP and the related terms STP and SWP: SIP, SWP and STP - what do they mean, which one should you choose and when?.

Given that we cannot predict the stock market, we need to make multiple assumptions regarding future returns and the ability of the investor to increase the SIP amount if the market does not move as per these assumptions. The final corpus will depend on the actual path followed by the stock market from now till the end.

We need to avoid uncertainty in predicting the final corpus figure. For example, if investing is for retirement, we need to know whether we will accumulate one crore as the corpus or ten crores. The quality of life in these two extreme cases will be very different.

Here is an example of a 15,000/month SIP run for 15 years. The SIP amount is increased by 5% every year as a step-up SIP. The chart shows ten different possibilities assuming the average equity return is 11% post-tax and risk of 15%. The results are:

• maximum value: ₹ 166 lakhs
• minimum value: ₹ 44 lakhs

We have deliberately omitted the y-axis from the chart since this level of variability is not effective in answering the question: how much we will get after 15 years?

Can we do better? But before that, you can use this calculator to see how a SIP can create wealth over time assuming fixed returns:

A better way

The variation in the previous case is the effect of market risk that shows us that the returns of the equity market are unpredictable. Since we need market risk to make high returns, we need a way to manage this risk. Rebalancing via a suitable asset allocation is the solution here which will be via allocating to equity and debt. For this example, we will invest 60% in equity and 40% in debt and keep this allocation fixed for 15 years by rebalancing annually. We will use the same sequence of equity returns as before.

As these results show (corpus range of ₹49-108 lakhs), the variability is now lower but still unpredictable.

The “best” way

Here we extend the concept of asset allocation and introduce the idea of the glide-path that will allow us to manage market risk. We start at 60% equity (the rest will be in debt) and gradually reduce that yearly until it drops to zero when you fully invest the corpus in debt.

We see that the range is finally predictable, as the results show with the corpus range of ₹60-66 lakhs. This example also shows the effect of diversifying the asset allocation and managing risk via rebalancing.

Summary of the three approaches

Case	Max corpus	Min corpus	Average	Variation
100% equity, no rebalancing	₹ 166	₹ 44	₹ 84	₹ 35
60:40 fixed asset allocation, rebalanced	₹ 108	₹ 49	₹ 72	₹ 17
Reducing equity asset allocation, rebalanced	₹ 66	₹ 60	₹ 63	₹ 2

In this article, we have covered how to estimate the returns for your SIP: How much returns should you estimate for your goals?

Using a SIP calculator that does this

We have designed a SIP calculator that supports reducing asset allocation and rebalancing as described above.

Using the example, a ₹15,000/month SIP increasing at 5% per year should reach a corpus of ₹62.31 lakhs, which is in line with the range of ₹60-66 lakhs we have seen before.

The calculator allows you to save for a shorter amount of time than the goal horizon by changing the “SIP for” value so that you can save for a goal without having income or investing during the last few years. The final corpus will be adjusted accordingly downwards as shown below:

We have reached a similar conclusion in this post where we have shown the probabilities of reaching a particular target return.

Caveat on these calculations

As we have seen in the figures above, there is some element of uncertainty associated with stock market investing, which can be minimized (at the cost of lowering potential returns) but not eliminated. The investor needs to revisit the portfolio at least once a year to check if they are on track and take remedial actions like rebalancing as per the glide path and modifying the SIP amount.

See this detailed post for the process for reviewing.

A note on the effects of inflation

The final corpus value after 15 years will have its purchasing power reduced due to inflation. The “Inflation adj. corpus (lakhs)” field shows the inflation-adjusted value. In our example, the ₹ 62.31 lakhs will be worth ₹ 22.58 lakhs (in today’s money) at 7% inflation. You can choose which inflation value you think applies to your goal.

Inflation: the impact on your goals and how to choose assets that beat it

Why you need to invest as per your goals

“Writing and tracking financial goals actually fuels the commitment required to achieve them” - Gaurav Rastogi, CEO of Kuvera

As discussed here, it is essential to set a goal before investing. While investors choose a SIP amount based on available capital, it is also critical to have a target corpus in mind before investing. The method allows you to check for progress and take remedial measures if you fall short of your target corpus.

Further reading

• What should be the Asset Allocation for your goals?
• Rebalancing portfolio during goal-based investing: why, when and how?
• Your portfolio needs a glide path: what, why and how?
• Set a goal before looking for what to invest in
• Never interrupt compounding by making these avoidable mistakes

Link to the Excel calculator: here