Why Starting to Invest Early Matters
The Math of a 10-Year Investing Head Start
One investor contributes $48,000. Another contributes $144,000. They earn the same return. The investor who started ten years earlier still ends up with more money at retirement.
11-minute read
Last updated September 2026
Quick Answer
Starting to invest early matters because it gives each dollar more time to compound. In this example, an investor who invests $400 a month for only ten years starting at age 25 finishes with more money at 65 than an investor who starts at 35 and contributes for the next thirty years.
Starting early is one of the few advantages in investing that does not require predicting what the market will do next. You do not need to find the next great stock, and you do not need to consistently earn a higher return than everyone else. You simply give the money you invest more time to grow.
There is a mathematical reason this matters. The compound-growth formula sits at the heart of The Long Math's logo, and in that formula, time is not just another variable: it sits in the exponent. The effect is that time is not simply additive, not even a simple multiplier. With a positive return, giving an investment more time allows its value to grow exponentially, as previous growth has the opportunity to generate further growth.
That sounds abstract, so consider what it means in real dollars.
Two investors, ten years apart
Imagine two people, both retiring at age 65 and both investing $400 per month whenever they are making contributions, earning the same hypothetical 8% effective annual return (converted to its equivalent monthly rate). The setup is deliberately uneven. Investor A gets a ten-year head start but contributes for only ten years. Investor B starts later but contributes for the next thirty years.
Investor A starts at age 25 and invests $400 every month for ten years, from age 25 until age 35. Then Investor A stops. No further contributions, ever. The money already invested simply remains invested until age 65.
Investor B does not start until age 35, then invests the same amount — $400 every month for the entire thirty years from age 35 until age 65.
Who contributed more? Who ends up with more?
Investor A: $48,000 contributed
Investor A contributes $400 × 12 months × 10 years, for a total of $48,000. After ten years, at age 35, the account has grown to approximately $72,050. While the contributions stop after age 35, the compounding does not. That $72,050 remains invested for another thirty years, and at an 8% annual return, by age 65 it grows to approximately $725,000.
Investor A contributed only $48,000 personally. The remaining roughly $677,000 came from investment growth.
Investor B: $144,000 contributed
Investor B does not invest anything between ages 25 and 35. At 35, Investor B begins contributing the same $400 per month and continues until age 65, contributing $400 × 12 months × 30 years, for a total of $144,000, three times as much money out of pocket as Investor A contributed. Every year, the growth keeps compounding.
At the same 8% annual return, Investor B reaches age 65 with approximately $563,000.
Here are the two investors side by side.
| Investor A | Investor B | |
|---|---|---|
| Starts investing | Age 25 | Age 35 |
| Stops contributing | Age 35 | Age 65 |
| Monthly contribution | $400 | $400 |
| Years contributing | 10 | 30 |
| Total contributed | $48,000 | $144,000 |
| Assumed annual return | 8% | 8% |
| Portfolio at 65 | ~$725,000 | ~$563,000 |
Investor B contributed $96,000 more and contributed for 20 more years. Investor B still finished about $162,000 behind.
Same monthly contribution. Same return. Investor B contributed three times as much. Investor A had one advantage though: more time for the early dollars to compound.
The first $48,000 had something the later money could not buy
It is tempting to look at these numbers and think the advantage came from Investor A earning a better return. It did not: both investors earned exactly the same assumed return. The advantage was that Investor A's earliest dollars had decades longer to compound. The $400 invested at age 25 had roughly 40 years to grow before age 65, while a $400 contribution made by Investor B at age 55 had only about ten. That difference becomes increasingly important because growth itself can generate additional growth.
Time does not guarantee a good investment result, but when an investment does produce positive long-term returns, more time gives compounding more opportunity to work.
Starting early can buy flexibility later
There is another way to look at Investor A's result. The benefit of starting at 25 was not merely a larger projected retirement account; it also created future flexibility. Because Investor A stopped contributing completely at age 35, the $400 per month that had previously gone toward investing could theoretically be redirected toward a mortgage, child care, education, a career change, working fewer hours, other savings goals, or simply more room in the household budget.
The example is intentionally extreme, chosen to isolate the value of the first ten years rather than to recommend that anyone stop saving for retirement at 35. What it illustrates is that money invested early can reduce how much work your future cash flow has to do. Starting early gives you options later.
What does Investor B need to do to catch up?
Waiting until 35 does not make catching up impossible, though it changes the arithmetic. Investor B has two obvious levers available: earn a higher return, or contribute more money. Consider both in turn.
Option 1: Earn a higher return
Suppose Investor B still contributes only $400 per month from age 35 to 65. Investor A's target is approximately $725,000, and at an 8% return, Investor B reaches only about $563,000. So what return would Investor B need to reach that same $725,000? Approximately 9.33% per year, or an additional 1.33 percentage points above Investor A's return.
An extra 1.33 percentage points may sound small to some, but sustained across 30 years, it increases Investor B's ending portfolio value by about 29%, from roughly $563,000 to $725,000.
Investor A needed 8%. Investor B needs about 9.33%. Future returns are uncertain. By comparison, the starting date is much more within the investor's control.
Option 2: Invest more each month
There is another way for Investor B to catch up: keep the same 8% assumed return, but increase the monthly contribution. To reach approximately $725,000 at age 65, Investor B would need to invest about $515 per month instead of $400, roughly 29% more every month. Over thirty years, Investor B would contribute approximately $185,000 to reach the same ending value produced by Investor A's original $48,000 of contributions.
| Catch-up strategy | Investor B needs |
|---|---|
| Same $400/month contribution | ~9.33% annual return |
| Same 8% annual return | ~$515/month |
Waiting still leaves the same destination reachable, though the trip becomes more expensive: it now requires more money, a higher return, or some combination of the two.
And what if Investor A never stopped?
So far, this comparison intentionally gave Investor A a substantial advantage and then took it away: Investor A started early but stopped contributing entirely after ten years. What happens if Investor A instead keeps investing $400 per month all the way from age 25 to age 65?
Total contributions would be $400 × 12 × 40, or $192,000. At the same hypothetical 8% annual return, the portfolio at age 65 would be approximately $1.29 million.
The three scenarios now look like this:
| Scenario | Total contributed | Portfolio at 65 |
|---|---|---|
| Start at 25, stop at 35 | $48,000 | ~$725,000 |
| Start at 35, invest until 65 | $144,000 | ~$563,000 |
| Start at 25, invest until 65 | $192,000 | ~$1.29 million |
The first ten years mattered. But the combination of starting early and continuing mattered even more.
A useful caveat: 8% is an assumption
This example is not a prediction of what any particular investment will earn. It assumes a steady 8% effective annual return in order to isolate one variable: time. Real investment returns vary from year to year, sometimes substantially. And, fees, taxes, investment choices, and the sequence of returns can all change the result.
The exact comparison also changes if the assumed return changes. At a 6% annual return, for example, Investor B's thirty years of contributions would slightly exceed the final value of Investor A's ten years of early contributions. That does not undermine the lesson; it helps define it. The higher the long-term compound return, the more valuable additional years of compounding become.
This is an illustration of the mathematics of time. With the contribution amounts and timelines held constant, whether the early ten years outperform the later thirty depends on the return achieved. As the assumed rate of return increases, the effect of additional time for compounding becomes increasingly significant.
The part you can control
Investors spend a great deal of time thinking about return. Which fund will perform better? Should I wait for prices to fall? Can I earn another percentage point? Those questions may matter, but future returns are uncertain.
Time is different. A 25-year-old cannot know what markets will return over the next 40 years, but that investor can decide whether the first contribution happens this year or ten years from now. And once a decade has passed, there is no investment that is guaranteed to make up that lost time.
Starting later can be overcome: you can save more, invest for longer, or earn higher returns. But each of those asks something additional from your future self. Starting earlier asks you to do something simpler and more controllable: give the money more time to grow.
Frequently Asked Questions
Why is starting to invest early so important?
Starting earlier gives each contribution more time to compound. Investment growth can itself generate additional growth, so the effect of additional years becomes increasingly significant over long periods.
In the example above, the investor who contributed $400 per month from age 25 to 35 invested only $48,000 but reached approximately $725,000 by age 65 at an assumed 8% annual return.
Is starting to invest at 35 too late?
No. This example illustrates the value of additional time. It does not imply a deadline for investing.
Someone who starts later can compensate by contributing more, investing longer, or achieving higher returns. In the example above, the 35-year-old could reach the same projected $725,000 by investing about $515 per month at the same 8% return.
How much difference can starting 10 years earlier make?
It depends on the contribution amount, investment return and how long the money remains invested.
In this example, starting at 25 rather than 35 allows $48,000 contributed during the first ten years to grow to approximately $725,000 by age 65. Someone starting at 35 and contributing $400 per month for the next 30 years contributes $144,000 but reaches approximately $563,000 at the same assumed return.
Does the person who starts earlier always end up with more money?
No.
The result depends on the return, contribution amount and contribution period.
This example specifically compares ten years of early contributions with 30 years of later contributions. At an 8% return, the early investor finishes ahead. At sufficiently lower returns, the additional contributions made by the later investor can outweigh the early head start.
The broader lesson is that additional time increases the potential effect of compounding.
Should I stop investing after 10 years if I start early?
No conclusion like that should be drawn from this example.
Stopping at age 35 is simply a way of isolating the value of the first ten years. When the early investor continues contributing $400 per month through age 65 in the same model, the projected portfolio grows to approximately $1.29 million.
Calculation assumptions
All examples assume:
- $400 contributions made at the end of each month
- an 8% effective annual return unless otherwise stated
- the annual return converted to its equivalent monthly rate using rm = (1 + ra)1/12 − 1 — not 8% / 12
- investment growth compounded monthly
- no taxes
- no investment fees
- no contribution increases with inflation
- no withdrawals
- all figures rounded to the nearest practical dollar or thousand
The monthly rate r sub m equals open parenthesis 1 plus r sub a close parenthesis to the power of 1 over 12, minus 1.
These are simplified illustrations, not forecasts of future investment returns.
Source and methodology note
The definition and general mechanics of compound growth — that compound interest includes growth on previously accumulated interest, and that starting earlier gives those returns more time to accumulate — are described by the Financial Consumer Agency of Canada in Planning and saving for retirement. That page supports the concept, not the portfolio values in this article.
All portfolio values and catch-up calculations in this article are mathematical projections using the assumptions listed above rather than historical market-return data. They are produced by the same ordinary-annuity math as the Cost of Waiting to Invest Calculator. They are not sourced from the FCAC.