# ₹5,000 a month for 20 years: what a SIP calculator can and cannot tell you

> Put in ₹12 lakh over two decades and the screen says ₹50 lakh. That number is real arithmetic and also a bit of a fairy tale. Here is how to read it without fooling yourself.

Published 2026-10-07 by Toolcloak. 5 minute read. Original: https://toolcloak.pages.dev/articles/5000-rupees-a-month-for-20-years-what-a-sip-calculator-can-tell-you
Related free tool: [SIP Calculator](https://toolcloak.pages.dev/tools/sip-calculator)

Type ₹5,000, 12 percent, 20 years into a SIP calculator and it answers **₹49,95,740**. You put in ₹12,00,000. The rest, nearly ₹38 lakh, is growth. It is a lovely number and it makes you want to start tomorrow.

It deserves a little suspicion, not because the arithmetic is wrong (it is perfectly right) but because of what you feed into it. A calculator multiplies your assumptions. It does not know whether they will come true. So the useful skill is not operating the calculator. It is knowing which of the numbers you can trust and which are a guess.

## First, what a SIP is not

A SIP, systematic investment plan, is not an investment. It is a **way of paying**: a fixed amount moves from your bank account into a mutual fund on a fixed date each month. What the money is invested in depends on the fund you choose. A SIP into an equity fund, a debt fund and a gold fund will give you three very different journeys.

This matters because the calculator asks for an “expected return”, and that number belongs to the fund, not to the SIP. Nobody can promise it.

## What the calculator is doing

Each month your money earns a month's worth of return, then your next ₹5,000 lands, then the whole pile earns again. That is compounding: growth earning growth. For a 12 percent yearly return, the calculator uses 1 percent per month.

**₹5,000 a month, two decades (value in lakh rupees)**

|  | Value if the fund grows 12% a year | Value if it grows 8% a year | Money you put in |
| --- | --- | --- | --- |
| 0 | 0 | 0 | 0 |
| 2 | 1.36 | 1.31 | 1.2 |
| 4 | 3.09 | 2.84 | 2.4 |
| 6 | 5.29 | 4.63 | 3.6 |
| 8 | 8.08 | 6.74 | 4.8 |
| 10 | 11.62 | 9.21 | 6 |
| 12 | 16.11 | 12.11 | 7.2 |
| 14 | 21.82 | 15.5 | 8.4 |
| 16 | 29.07 | 19.49 | 9.6 |
| 18 | 38.27 | 24.16 | 10.8 |
| 20 | 49.96 | 29.65 | 12 |

*Years on the bottom. The grey dashed line is simply what you deposited. The gap above it is growth. Notice how late the curve takes off.*

Look at the shape. For the first ten years the curve hugs the line of your own deposits. At year 10 you have put in ₹6 lakh and have ₹11.6 lakh. Then it bends. Between year 15 and year 20, the value goes from ₹25.2 lakh to ₹49.96 lakh. **The last five years add almost as much as the first fifteen put together.**

That is the whole secret, and it is also the most boring advice there is: the biggest part of the result comes from the part where nothing seems to be happening. People who stop at year six, because it feels slow, quit just before it gets interesting.

Try it: [SIP Calculator](https://toolcloak.pages.dev/tools/sip-calculator). Monthly amount, expected return, years. Add a yearly step-up to see what raising your SIP does.

## Time beats amount

| Years | You put in | Value at 12% a year | Value at 8% a year |
| --- | --- | --- | --- |
| 5 | ₹3,00,000 | ₹4.12 lakh | ₹3.70 lakh |
| 10 | ₹6,00,000 | ₹11.62 lakh | ₹9.21 lakh |
| 20 | ₹12,00,000 | ₹49.96 lakh | ₹29.65 lakh |
| 30 | ₹18,00,000 | ₹1.76 crore | ₹75.0 lakh |

*Same ₹5,000 a month in every row. Only the number of years changes. The 8% column uses the same formula with a lower assumed return.*

Compare 20 years with 30. You deposit 50 percent more money (₹18 lakh instead of ₹12 lakh) and end up with **3.5 times** as much. Starting ten years later and doubling the SIP does not catch you up. Time is the one input you cannot buy back.

## Three honest corrections

### 1. The return is an assumption

Equity funds have, over long periods, delivered returns in the ballpark people quote. They do it unevenly: a year of 30 percent, a year of minus 15. The calculator draws a smooth line through all that. Your real journey will be bumpy, and the end value at any particular date can be well above or below the smooth line.

That is why you should always run the calculator **twice**: once with the number you hope for, once with a number that would disappoint you. If the disappointing version still gets you where you need to be, you have a plan. If only the hopeful version works, you have a wish.

### 2. Inflation eats the final number

₹49.96 lakh in 20 years is not ₹49.96 lakh of today's buying power. At 6 percent yearly inflation, it is worth about **₹15.6 lakh** in today's money. Still good. Just not what the headline implies. When you set a goal, decide whether it is “₹50 lakh” or “what ₹50 lakh buys today” and calculate accordingly.

### 3. Costs and tax are not in there

Fund expenses are deducted from the fund's returns, and gains are taxed when you sell. The calculator shows neither. Treat its answer as the number before costs and before tax.

> **Calculators are not guarantees:** Mutual fund investments are subject to market risk, and past returns do not predict future ones. This article explains how the arithmetic works. It is not investment advice, and we are not licensed financial advisers.

## The step-up trick

Most people's income grows. Their SIP often does not, because nobody remembers to change it. The calculator has a yearly step-up option for exactly this.

Start with the same ₹5,000 but raise it by 10 percent every year (₹5,500 in year two, ₹6,050 in year three, and so on). At 12 percent for 20 years you deposit about **₹34.4 lakh** in total, and the value comes to about **₹99.4 lakh**. That is double the flat SIP result, for a monthly increase you would barely notice in any single year.

The easy way to do it: every time you get a raise, move a slice of the raise into the SIP before you get used to spending it.

## Why monthly, and why bother

When the market falls, your fixed ₹5,000 buys more units. When it rises, it buys fewer. Over time your average purchase price ends up lower than the average price, a mechanical effect often called rupee-cost averaging. It does not remove risk. What it does is remove the temptation to wait for “the right time”, which nobody has ever reliably found.

The deeper benefit is behavioural. A SIP that runs automatically on the 5th is one fewer decision you can talk yourself out of when the news is bad.

## How to use the calculator well

1. Start with a **goal and a date**, not an amount. “₹25 lakh for a down payment in 12 years” beats “whatever I can spare”.
2. Run two returns: one you hope for and one that would hurt a little.
3. Subtract inflation from your goal in your head, or inflate the target upward.
4. Turn on the **step-up** and pick a number you can honestly commit to.
5. Set it up, then leave it alone. Look at it once or twice a year.

## Frequently asked questions

### How is SIP return calculated?

The calculator treats each monthly instalment as earning the expected return for the remaining months. For a 12 percent yearly return it uses 1 percent a month, adds each instalment as it is paid, and lets the whole balance compound. The answer is the total value at the end of the period.

### How much will ₹5,000 a month grow to in 20 years?

At an assumed 12 percent a year, about ₹49.96 lakh on ₹12 lakh invested. At 8 percent, about ₹29.65 lakh. These are estimates from the formula, not promises, and real returns vary year to year.

### Is 12 percent a safe number to assume?

It is an assumption, not a guarantee. It is sensible to run the calculator with a lower return as well, so your plan still works if markets disappoint.

### What is a step-up SIP?

A SIP whose amount increases by a set percentage every year. With a 10 percent step-up starting at ₹5,000, you invest about ₹34.4 lakh over 20 years instead of ₹12 lakh, and at 12 percent the estimated value roughly doubles to about ₹99 lakh.

### Does the calculator include tax and fund charges?

No. It shows the growth before expenses and before tax, so your actual result will be somewhat lower.