Investing regularly can make a significant difference to your long-term finances, even if you do not start with a large lump sum. For example, investing ₹1 lakh every year means putting aside about ₹8,333 per month on average.

If this habit continues for 15 years, your total investment will be ₹15 lakh.

But will ₹15 lakh invested over time grow to ₹25 lakh, ₹35 lakh or even more than ₹40 lakh?

The answer depends largely on where the money is invested and the return it earns.

To understand the impact, consider three popular investment options—Fixed Deposits (FDs), National Pension System (NPS) and mutual funds. Using the assumptions in the source, let us compare how ₹1 lakh invested every year for 15 years could potentially grow.

₹1 Lakh Every Year Means ₹15 Lakh Invested

The basic calculation is straightforward.

Annual investment: ₹1 lakh
Investment period: 15 years
Total amount invested: ₹15 lakh

However, the money invested in the first year gets considerably more time to grow than the contribution made in the fifteenth year.

This is where compounding becomes important.

As returns accumulate, they can potentially generate additional returns over subsequent years. Over a long period, even a relatively small difference in the assumed annual rate can result in a large difference in the final corpus.

FD: How Much Could ₹1 Lakh a Year Become?

For the FD calculation, the source assumes an annual interest rate of 7.1%.

If ₹1 lakh is invested every year at the assumed rate for 15 years, the projected corpus could reach approximately ₹27.12 lakh.

Of this:

• Total amount invested: ₹15 lakh
• Estimated interest earned: ₹12.12 lakh
• Projected corpus: ₹27.12 lakh

The source makes it clear that this is only an illustration. Actual FD returns will depend on the interest rate offered by the bank, tenure and method of compounding.

Another practical issue is that maintaining exactly the same 7.1% return for every annual investment over 15 years cannot be guaranteed. FD rates can change over time.

Therefore, ₹27.12 lakh should be treated as a hypothetical calculation rather than a guaranteed maturity amount.

Why Might Investors Choose an FD?

Fixed deposits are generally preferred by investors who place greater importance on predictability and lower risk than on maximising market-linked returns.

Once an FD is booked, its applicable interest rate is generally fixed for the selected tenure, subject to the bank's terms.

However, repeatedly investing ₹1 lakh every year would normally mean creating deposits at the rates available at different points in time.

FD interest is also subject to applicable income-tax provisions. Therefore, the post-tax return could be lower than the headline interest rate.

NPS: ₹15 Lakh Investment Could Potentially Reach ₹34.95 Lakh

The National Pension System works differently from an FD.

NPS does not provide a fixed interest rate. Contributions are invested across permitted asset classes such as equities, corporate debt and government securities.

Returns therefore depend on market performance and the asset allocation of the investor.

For illustration, the source assumes an average annual return of 10%.

At that assumed return, investing ₹1 lakh every year for 15 years could potentially create a corpus of approximately ₹34.95 lakh.

The calculation given is:

Total investment: ₹15 lakh
Estimated gains: ₹19.95 lakh
Projected corpus: ₹34.95 lakh

This is approximately ₹7.83 lakh more than the FD corpus calculated using the source's assumptions.

However, the 10% return is not guaranteed.

Why Is NPS Different From an FD?

NPS is primarily a retirement-oriented investment system.

Because part of the portfolio can be exposed to market-linked assets, returns can fluctuate. The eventual corpus will depend on factors such as asset allocation, investment performance and the length of time the money remains invested.

Therefore, comparing NPS and FD solely by using 10% versus 7.1% can be misleading if risk and product structure are ignored.

NPS also has specific rules governing withdrawals and retirement benefits, making it fundamentally different from an ordinary bank deposit.

Mutual Funds: ₹1 Lakh a Year Could Potentially Become ₹41.75 Lakh

Now consider the third scenario.

For mutual funds, the source assumes an average annual return of 12%.

Under this assumption, investing ₹1 lakh annually for 15 years could potentially create a corpus of around ₹41.75 lakh.

The source's illustration gives:

Total investment: ₹15 lakh
Estimated gains: ₹26.75 lakh
Projected corpus: ₹41.75 lakh

This is substantially higher than the FD and NPS figures in the example.

However, there is a critical point to remember: 12% is an assumed return, not a guaranteed mutual fund return.

Mutual fund performance is linked to the underlying investments and market conditions. Actual returns could be higher or lower, and losses are also possible.

FD vs NPS vs Mutual Funds: Full Calculation

Using the assumptions provided in the source, the comparison looks like this:

Under these assumptions, the difference between the FD and mutual fund corpus is approximately ₹14.63 lakh.

The projected NPS corpus is approximately ₹7.83 lakh higher than the FD corpus.

Why Does a Small Difference in Returns Matter So Much?

At first glance, the difference between 7.1%, 10% and 12% may not appear enormous.

But over 15 years, compounding magnifies that difference.

The longer money remains invested, the greater the opportunity for accumulated returns to generate additional returns.

This explains why the same ₹15 lakh of total contributions can theoretically produce very different final amounts.

The source highlights this compounding effect as the key reason differences in annual returns become increasingly significant over long investment periods.

Does This Mean Mutual Funds Are Always Better?

No.

Looking only at the projected final corpus would ignore one of the most important principles of investing: higher potential returns generally come with different levels and types of risk.

The FD figure is based on a relatively predictable interest-rate assumption, while NPS and mutual fund returns are market-linked.

A mutual fund does not promise 12% every year. Returns can vary substantially from year to year.

There could be periods of strong gains, weak performance or negative returns.

Therefore, ₹41.75 lakh should be understood as the result of a mathematical assumption—not an assured maturity value.

Which Option May Suit Which Investor?

The source broadly distinguishes the three options according to their characteristics.

FDs may appeal to investors who want comparatively predictable returns and lower risk. NPS is specifically designed for retirement planning and provides market-linked exposure through different asset classes. Mutual funds are also market-linked and can offer higher return potential over longer periods, depending on the type of fund and market performance.

The right option therefore depends on much more than the projected corpus.

An investor should consider risk tolerance, investment horizon, liquidity requirements, tax treatment and the purpose for which the money is being accumulated.

You Don't Necessarily Have to Pick Only One

The comparison should also not be interpreted as meaning an investor must put the entire ₹1 lakh annual investment into just one product.

Different investment products can serve different financial objectives.

For example, someone may want relatively stable savings for a short- or medium-term requirement, a separate retirement corpus and market-linked investments for long-term wealth creation.

The appropriate allocation depends on the individual's circumstances.

Regular Investing Can Matter as Much as the Return

Another important lesson from this example is the value of consistency.

Investing ₹1 lakh in one year and then stopping is very different from investing the same amount every year for 15 years.

Regular investing ensures that more capital is gradually put to work, while earlier contributions get longer periods to compound.

This means building wealth is not necessarily about finding the investment with the highest advertised return. Time, discipline and consistency can be equally important.

The Bottom Line

If you invest ₹1 lakh every year for 15 years, your total contribution will be ₹15 lakh.

Using the assumptions in the source, that money could theoretically grow to approximately ₹27.12 lakh in an FD at 7.1%, ₹34.95 lakh in NPS at a 10% average return, or ₹41.75 lakh in mutual funds at a 12% average return.

But these numbers should not be interpreted as guaranteed outcomes.

FD rates can change, while NPS and mutual fund returns depend on market performance. Taxation, costs, product rules and the timing of annual investments can also affect the final amount.

So, rather than choosing an investment simply because its projected corpus looks larger, consider your financial goal, investment period, liquidity needs and ability to handle risk.

Disclaimer: The calculations are illustrative and based on the return assumptions stated above. NPS and mutual fund returns are market-linked and are not guaranteed. Actual FD returns can also vary according to prevailing interest rates, tenure and compounding. This article is for general information only and should not be considered investment advice.