Investment & Compound Interest Calculator

Project the future value of your portfolio by entering your initial capital and monthly contributions to see how compound interest grows your wealth over your chosen time horizon.

How this investment calculator works

How much do you need to invest to get to your goal? Use this calculator to get the future value of your investments based on different rates of return.

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Key factors to consider before investing

Here’s how to decide on an investment, based on some basic key metrics. For the purposes of this discussion, we’ll compare investing in real estate and an entry-level product in the capital market – Exchange Traded Funds (ETFs).

1. Initial capital

The amount of initial capital required to invest in either of these options is one of the biggest deciding factors.

The cost for a downpayment of a residential property in Singapore starts at several hundred thousand dollars.

Then, there’s the cost of mortgage loans and your eligibility for those.

However in the case of ETFs there are many different initial capital requirements for various options. You can start by investing as little as $30.

2. Need for liquidity

Real estate, given that it is tangible, immovable, also not fractionable, is usually considered highly illiquid. The sale of the property often comes with costs too. In most markets, sellers are required to pay a fee of 1%-3% of the selling price to real estate agents for their services.

The time taken to sell a property may range from 1 week to 1 year (based on personal experience) in markets with an oversupply of options for buyers. So just be prepared to continue with the mortgage loans in the meantime. You can calculate your potential mortgage loans here.

ETFs, on the other hand, are considered to be highly liquid. The time taken to sell your investment is usually 3 days. Also, there’s usually little to no charges incurred when you sell as most platforms usually charge a sales fee but not a sell fee.

3. Rate of return

The average rate of return for the Singapore resale property market from Jan 2009 to Dec 2018 (10 years) was 88.4%.

While the average rate of return for the SPDR Straits Times Index ETF (for the sake of comparison) in the same time frame was 107.16%.

For a highly liquid investment like ETFs, prices are easily and frequently tracked. Conversely, most people don’t track the value of their property as frequently or easily. It’s important to note that the beauty in value investing is that you don’t need to track it everyday, you should only have to check it once a month and review the performance semi-annually.

4. Tangibility

Tangibility doesn’t relate to any form of higher rate of return. It does however give us a sense of security which results in a greater emotional attachment. So, depending on your investment priorities, you may want to consider excluding this factor if you want to make less emotionally driven investments.

The power of compounding and why starting early matters

Waiting to invest is the most expensive mistake you can make. In 2026, with rising core inflation and a “K-shaped” economy, the gap between those who start early and those who wait is wider than ever.

The “Cost of Waiting” is Real

Starting just 10 years earlier can result in a portfolio nearly twice as large for the same total contribution.

For example, a $500 monthly investment from age 25 can grow to ~$760,000 by 65, while someone starting at 55 would need to invest S$2,000 monthly, four times the effort just to reach less than half that amount.

Shield your money from inflation

With 2026 inflation projected at 1–2%, cash sitting in a zero-interest account is losing value every day.

Compounding allows your returns to “snowball,” ensuring your wealth grows faster than the cost of living.

The Rule of 72

Want to know how fast your money doubles? Divide 72 by your expected return. At a 6% return, your money doubles every 12 years (72/6 = 12). If you wait 12 years to start, you’ve missed an entire doubling cycle.

The most important factor isn’t the amount you start with, but the time you give it to work.

Frequently asked questions (FAQ)

1. What is the difference between Simple and Compound Interest?

Simple interest is calculated only on your initial deposit. Compound interest is “interest on interest”. It means your earnings are reinvested to generate their own returns. Over 20–30 years, compounding can account for more than half of your total portfolio value.

2. Is it better to wait until I have a large sum to start investing?

No. Because of compounding, time is more valuable than capital. Starting with $100 a month today is almost always better than waiting five years to start with $500 a month. Those five missed years are “lost cycles” where your money could have been doubling.

3. What is a “realistic” annual return rate to use in the calculator?

While markets fluctuate, historical benchmarks for 2026 planning are:

Conservative (Cash/Bonds): 2% – 4%
Moderate (Balanced Portfolios): 5% – 7%
Aggressive (All-Equity/ETFs): 8% – 10%

Always remember that past performance does not guarantee future results.

4. Does the frequency of compounding matter?

es, but the impact is higher over long periods. Most savings accounts compound daily or monthly, while most investments are measured annually. Our calculator defaults to annual compounding to provide a conservative estimate that aligns with most long-term stock market projections.