How to Build a Retirement Plan from Scratch

Most people guess — and most people guess wrong

Over three decades of financial planning, I sat across the table from hundreds of people who wanted to retire comfortably. The ones who struggled almost always had the same problem: they never put a number on it. They saved “whatever was left over” and hoped it would be enough. It rarely was.

The ones who did well weren’t necessarily higher earners. They were the ones who picked a target number, built a plan around it, and adjusted course along the way. That’s what this guide is about — turning a vague goal like “retire someday” into a concrete, measurable plan with real numbers attached to it.

Step 1: Figure out how much you actually need

The standard rule of thumb is that you’ll need about 80% of your pre-retirement income each year in retirement. If you earn $75,000 a year, that’s $60,000 annually. If you expect to be retired for 25 years, you’re looking at $1,500,000 — and that’s before you account for inflation or healthcare costs.

But rules of thumb only get you so far. Your actual number depends on where you live, whether your home is paid off, what kind of healthcare coverage you’ll have, and how you plan to spend your time. Someone who wants to travel extensively will need more than someone who plans to garden and read.

Let’s use the Retirement Calculator to establish your personal target. Enter your current age, expected retirement age, current savings, and anticipated expenses to see where you stand:

If the gap between what you have and what you need looks intimidating, don’t panic. That gap is information, not a verdict. I’ve worked with clients who were $400,000 short at age 45 and closed the gap entirely by age 62 through disciplined saving and smart allocation. The earlier you identify the shortfall, the more time you have to address it.

Step 2: Maximize your 401(k) — it’s the best tool most people underuse

If your employer offers a 401(k) with a match, that match is the single best return on investment available to you. An employer who matches 50% of your contributions up to 6% of your salary is giving you a guaranteed 50% return on that money before it ever hits the market. There is no stock, bond, or real estate investment that can promise that.

In 2026, you can contribute up to $23,500 to a 401(k) if you’re under 50, or $31,000 if you’re 50 or older. Most people contribute just enough to get the match and stop there. If your budget allows, pushing beyond the match accelerates your timeline significantly.

Here’s a concrete example from my own experience. When my two kids were in college simultaneously, I dropped my 401(k) contribution to the match minimum — about 6% of my salary. Once the tuition bills stopped, I bumped it to 15%. Those extra percentage points over the following twelve years added roughly $180,000 to my retirement balance, including market growth.

Let’s use the 401(k) Calculator to model how different contribution levels affect your outcome. Try adjusting the contribution percentage and employer match to see the difference over time:

A few things worth noting when you look at those projections. First, the tax deferral matters. Every dollar you contribute reduces your taxable income today, so a $1,000 contribution doesn’t actually reduce your paycheck by $1,000 — it reduces it by something closer to $750 or $800, depending on your tax bracket. Second, if your employer offers a Roth 401(k) option, contributions are after-tax but withdrawals in retirement are tax-free. The right choice depends on whether you expect to be in a higher or lower tax bracket when you retire.

Step 3: Understand the engine behind it all — compound interest

Compound interest is the mechanism that turns modest, consistent contributions into a large sum over time. It’s not complicated, but its effects are genuinely difficult to grasp intuitively. Our brains think in straight lines. Compound growth is a curve.

Here’s an example I used to share with clients. If you invest $500 a month starting at age 25 and earn an average annual return of 7%, you’ll have roughly $1,200,000 by age 65. If you wait until age 35 to start — just ten years later — you’ll have about $567,000. Same monthly contribution, same return, but half the result. That missing $633,000 is the cost of waiting.

The reverse is also encouraging. Even small increases in your monthly savings have outsized effects over long periods. Going from $500 to $600 a month — an extra $100 — adds approximately $240,000 over 40 years at that same 7% return.

Let’s use the Compound Interest Calculator to see this in action. Enter different starting amounts, monthly contributions, and time horizons to see how the numbers change:

Pay attention to the breakdown between what you actually contribute and what the interest earns. In long-horizon scenarios, the interest often exceeds the total amount you personally put in. That’s the compounding doing its work — your money earning money on its money.

Putting the three pieces together

A retirement plan isn’t one decision. It’s three decisions working in concert:

1. Your target number — what you need to save in total, based on your expected expenses and retirement timeline
2. Your savings vehicle — primarily your 401(k), IRA, or other tax-advantaged accounts, where employer matches and tax benefits amplify every dollar
3. Your time horizon — the number of years compound interest has to work, which is the single most powerful variable in the equation

The most effective thing you can do right now is run your numbers through all three calculators above and write down what you find. Not a mental note — an actual written record. What’s your target? What are you contributing? What’s the projected gap?

Then revisit those numbers once a year. Life changes — salaries go up, expenses shift, markets move. I used to do this every January with my own plan, and I’d adjust my contribution rate or allocation based on what the numbers showed. It took about thirty minutes, and it kept me on track through two kids’ college educations, two mortgage refinances, and a career that lasted longer than I originally planned.

One last thing I tell everyone

Start today. Not next month, not after the next raise, not once the car is paid off. The math doesn’t care about your reasons for waiting — it only cares about time. Every month you delay is a month of compounding you don’t get back. Even $50 a month is better than $0, and you can always increase it later.

The volunteers I work with at the financial literacy nonprofit where I spend my Tuesdays often say they wish someone had told them this twenty years ago. I’m telling you now.