Why Starting Early Matters

Retirement is the largest purchase most people ever make, and it is paid for decades in advance. This chapter answers two questions: why time matters more than almost any other input, and why so many people who know this still put off starting. Understanding the second question is what makes the first one useful.

Time does much of the work

Money invested for retirement grows in two ways. You add to it, and what is already there earns a return, which then earns its own return. That second effect is compounding, and its strength depends almost entirely on how many years it runs.

The examples below use the engine behind our calculators. They assume a portfolio that earns 7% a year before inflation, with 3% inflation, so it grows by about 3.9% a year in today's dollars. The target is a portfolio that could pay out a fixed amount each year at a 4% withdrawal rate; chapter 3 explains where that idea comes from.

Saving $800 a month from a standing start reaches a target of $1,000,000 in about 42.2 years. Now suppose someone waits ten years before starting but still wants to finish at the same age. They have ten fewer years, so they must save more each month.

To reach the same $1,000,000 in about 32.5 years, the monthly amount has to rise from $800 to $1,300. The ten years of delay are paid for with a permanently higher saving rate, and the later saver also puts in more of their own money in total, because there are fewer years of growth to do the rest.

The reverse is also true. Doubling the monthly amount to $1,600 does not halve the wait: it falls to about 28.8 years. Time and money are both inputs, but time is the one you cannot buy back later.

A useful rule of thumb here is the rule of 72: divide 72 by a yearly growth rate to get roughly how many years it takes money to double. At about 3.9% a year after inflation, that is about 18 or 19 years. A sum invested in your twenties can double in real terms more than twice before a usual retirement age. The same sum invested in your fifties may not double even once.

These are steady-return illustrations. Real markets rise and fall, sometimes sharply, and nobody can promise any particular return. The point is the shape of the curve, not the exact figures.

Why people put it off anyway

If the maths is this clear, why do so many people start late? Behavioral economists have studied the question for decades, and a few patterns explain most of it.

Present bias. People weigh what happens today far more heavily than what happens in thirty years. Spending gives a reward now; saving gives a reward to a future person who can feel like a stranger. This is a normal feature of how people make decisions, not a character flaw, which is why the most reliable fixes work around it rather than relying on willpower.

Too many choices. A workplace plan with dozens of funds, plus the choice between traditional and Roth, plus the question of how much, can make doing nothing feel like the safest option. In practice, doing nothing is a choice too, and usually the most expensive one.

Loss aversion. Losses hurt more than equal gains feel good. Someone who watches a balance fall in a bad year may stop contributing or move to cash at the worst moment. Over a long horizon, the bigger risk for most savers is not a market fall but having too little invested for too short a time.

Comparison with others. Spending tends to rise to match the people around us, and to match each raise. When every pay increase becomes a higher standard of living, the saving rate never moves. That pattern has a name, lifestyle creep, and it is covered in the glossary at /learn/glossary.

What actually works

The research points to a handful of methods that work because they do not depend on remembering or feeling motivated.

Automatic enrollment and automatic contributions. Madrian and Shea (2001) studied a company that switched its 401(k) from opt-in to automatic enrollment. Participation rose sharply, mostly because people stayed with whatever the default was. You can use the same effect on yourself: set the contribution once through payroll, so saving happens before the money reaches your account.

Committing future raises. Thaler and Benartzi (2004) tested a program called Save More Tomorrow, in which employees agreed in advance to raise their contribution rate each time they got a raise. Because the increase came out of money they had not yet started spending, it did not feel like a loss, and saving rates rose substantially over the following years. Many plans now offer an automatic yearly increase that does the same thing.

Starting with something small. A contribution of a few percent of pay is far better than a plan to contribute more later. The first contribution sets up the account, the investment choice and the habit. Raising the rate afterwards is a single change on a form.

One simple investment choice. Most workplace plans offer a target-date fund, which holds a mix of stocks and bonds that becomes more conservative as the target year approaches. It is not the only sensible choice, but it removes the decision that stops many people from starting at all. Chapter 5 looks at investment choices and fees.

Looking at the number, not the noise. Checking a balance daily invites the loss-aversion reaction described above. A yearly review of the saving rate and the plan, rather than the market, keeps attention on the inputs you control.

How much is enough to start

There is no single right first amount. A common starting point is whatever earns the full employer match, if your employer offers one, because that money is part of your pay and is lost if you do not contribute. Chapter 5 explains how matches work and why they usually come first.

Beyond that, the share of income you save, your savings rate, is the lever that matters most over a working life. It sets both how fast the portfolio grows and how much spending it will eventually need to support. The savings rate calculator shows your current rate and how changing it moves the time to your goal.

If you are starting later than you would like, the lesson of the examples above is not that it is too late. It is that each year from now on is worth more than any single year in the future, so the best time to begin is the next payday.