Retirement Savings Gap Before 40: The 4-Step Math to Check

Michael Chen

Michael Chen writes about personal finance fundamentals. Bay Area-based · finance enthusiast for 15 years.

Visual representation of the voice · not a photographic portrait

Quick answer: To calculate your retirement savings gap, estimate the yearly income you want in retirement, multiply it by 25 to get your target nest egg, then project what your current savings and contributions will grow to by your retirement age. The difference between the two numbers is your gap. Most people can do this in about 20 minutes with a calculator.↗ Share on X

Your retirement savings gap is the difference between the money you will likely have at retirement and the money you will actually need. You can calculate it in four steps: decide the yearly income you want, multiply it by 25 to get a target, project your current savings forward, and subtract. Doing this before age 40 matters because every year you wait removes one of the most powerful years of compound growth you will ever have.

This article walks through the four steps with a worked example, shows a table you can copy, and explains what to do if the result is scary. Nothing here is personal financial advice. It is a method for seeing your own numbers clearly. If you have a complex situation, such as a pension, a business, or debt that is hard to manage, a licensed financial planner can run this with far more precision.

Step 1: How much yearly income will you need in retirement?

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Start with what you spend now, not what you earn. Most people spend less in retirement than during working years because the mortgage may be paid off, children may be independent, and commuting costs disappear. A common planning rule is to aim for 70 to 80 percent of your current spending.

Here is the simple way to estimate it:

1. Add up your spending for the last three months. Use your bank and card statements, not your memory.

2. Divide by three to get a monthly figure. Multiply by 12 for a yearly figure.

3. Multiply that yearly figure by 0.75.

Example: you spend 4,000 dollars per month. That is 48,000 dollars per year. Multiply by 0.75 and your retirement income target is 36,000 dollars per year in today's money.

If you expect to receive Social Security or a government pension, you can subtract the expected yearly amount. In the United States, you can see your estimated benefit by creating an account at the Social Security Administration website. If you are unsure, leave it out for now. It is safer to plan without it and treat it as a bonus.

Step 2: What is your target nest egg?

Take the yearly income from Step 1 and multiply it by 25. This is known as the 4 percent rule. The idea is that if you withdraw about 4 percent of your savings in the first year of retirement, and adjust for inflation after that, your money has a good chance of lasting 30 years.

Example: 36,000 dollars times 25 equals 900,000 dollars. That is the target nest egg.

The 4 percent rule is a planning shortcut, not a promise. Some researchers argue for 3.5 percent to be safer, which would mean multiplying by about 28 instead of 25. Others accept 4.5 percent. For a first check before age 40, 25 is a reasonable middle number. You will refine it later.

Step 3: What will your current savings grow to?

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Now project what you already have, plus what you add each year, forward to your retirement age. You need three inputs:

• Current savings: everything in retirement accounts and investments meant for retirement.
• Yearly contributions: what you and any employer add per year.
• Years until retirement: your retirement age minus your current age.

You also need a growth rate. Use a real rate, meaning after inflation, so the result is in today's money and can be compared with your Step 2 target. A real rate of 4 to 5 percent per year is a common planning assumption for a portfolio mostly in low-cost index funds. Use 4 percent if you want to be careful.

The table below shows roughly what 1 dollar grows to at 4 percent real, and what 1 dollar saved every year grows to. Multiply your own numbers by these factors.

Example: you are 35, you plan to retire at 65, so you have 30 years. You have 60,000 dollars saved and you add 7,000 dollars per year including your employer match.

• Current savings: 60,000 times 3.24 equals about 194,000 dollars.
• Contributions: 7,000 times 56.08 equals about 393,000 dollars.
• Projected total: about 587,000 dollars in today's money.

Step 4: What is your gap?

Subtract the Step 3 projection from the Step 2 target.

Example: 900,000 minus 587,000 equals a gap of about 313,000 dollars.

That number looks large, but the next question is the one that matters: how much extra per year closes it? Divide the gap by the "1 dollar saved per year" factor for your time horizon.

Example: 313,000 divided by 56.08 equals about 5,600 dollars per year, or roughly 465 dollars per month, starting now and continuing for 30 years.

So the person in this example is not in trouble. They need to raise their yearly saving from 7,000 to about 12,600 dollars. That is a real change, but a clear and reachable one, especially if income rises over the next decade.

Why does doing this before 40 change the answer so much?

Compound growth works harder on money that has more years to grow. Look at what happens to the same 5,600 dollars per year if the person in the example waits.

Waiting ten years almost doubles the yearly amount needed. Waiting fifteen years nearly triples it. This is the whole reason to run the numbers now, even if the answer is uncomfortable.

What if the gap is much bigger than you expected?

A large gap is information, not a verdict. There are five levers, and most people pull more than one.

1. Raise contributions gradually. Increase your saving rate by 1 percent of income every six months. Many people do not feel a 1 percent change.

2. Capture the full employer match. If your employer matches contributions and you are not getting all of it, that is free money you are leaving behind.

3. Lower investment costs. A fund that charges 1 percent per year instead of 0.1 percent can take a meaningful share of your final balance over 30 years. Check the expense ratio on every fund you own.

4. Adjust the target. Review Step 1. Can you live well on a bit less? Could part-time work in the first years of retirement cover a portion of your income?

5. Move the date. Retiring at 67 instead of 65 adds two years of growth and contributions and removes two years of withdrawals. The effect on the gap is larger than most people expect.

If after these changes the gap still looks impossible, that is the moment to talk to a licensed financial planner, ideally one who charges a flat fee rather than a commission. If you carry high-interest debt, a nonprofit credit counselor can help you build a plan to pay it down first, because debt at 20 percent interest will beat any investment return.

Which numbers should you not trust in this calculation?

Be honest about the weak spots so you can revisit them each year.

• Your growth rate. Markets do not return a smooth 4 percent. Some decades are far better, some far worse. Run the table again with 3 percent to see a cautious case.
• Your spending. Health costs tend to rise with age. Add a cushion if you have no employer or government health coverage planned.
• Inflation. The method uses real returns so you can think in today's dollars, but your actual contributions will need to rise with inflation to keep pace.
• Taxes. Money in pre-tax accounts will be taxed when withdrawn. If most of your savings are pre-tax, consider raising your target by 15 to 25 percent.

None of these make the exercise useless. They mean you should repeat it every year, on the same date, and watch the trend.

Your next step this week

Open a note on your phone and write down four numbers: your monthly spending, your current retirement savings, your yearly contributions, and the age you want to stop working. Then spend 20 minutes running the four steps above with the multiplier table. Write the gap and the extra monthly amount at the bottom of the note and date it. Next, log in to your retirement account and raise your contribution by at least 1 percent of income today. Set a reminder to redo the calculation one year from now and compare the two notes.

FAQ

Is the 4 percent rule still safe to use for retirement planning?

It is a planning shortcut, not a promise. Some researchers suggest 3.5 percent for a longer retirement or lower expected returns. For a first check before age 40, multiplying your yearly income need by 25 is a reasonable starting point that you can adjust as you learn more.

Should I include Social Security in my retirement gap calculation?

You can subtract your estimated yearly benefit from your income target, which shrinks your nest egg goal. If you are unsure of the amount or worried about future changes, leave it out and treat any benefit as extra safety margin.

What growth rate should I use when projecting my savings?

Use a real rate, meaning after inflation, so your result is in today's dollars. A range of 4 to 5 percent is a common assumption for a low-cost index fund portfolio. Run the numbers at 3 percent as well to see a cautious scenario.

Educational content, not personalized financial advice. Sources cited where applicable.