Tools FI Number & Retirement Gap

Free tool · FI Number & Retirement Gap

How much do you need to retire, and are you on pace?

Your FI number is the amount that could fund your spending for good: financial independence. Find yours with the 4% rule, project your savings to the age you want to stop, and see exactly what it would take to close any gap.

By · Updated

Step 1 · Your timeline

Step 2 · Spending in retirement

In today’s dollars. Many people plan on 70–80% of what they spend now.
Social Security, a pension, or rental income. Your Social Security estimate is at ssa.gov/myaccount.

Step 3 · Your savings

401(k), IRA, and other long-term investments.
Include any employer match. 0 if none.
Leave blank for 5% a year, a common long-run planning figure for a stock-heavy mix.

Private by design: everything is calculated in your browser. Nothing you type is saved or sent.

How this calculator works

FI number = (yearly spending − other retirement income) × 25

Multiplying by 25 comes from the 4% rule: historically, a diversified portfolio has supported withdrawing about 4% in the first year, then the same amount adjusted for inflation, for at least 30 years in most periods studied. If you’ll need $36,000 a year from savings, your FI number is $900,000.

The projection grows today’s savings and your monthly contributions at your expected return after inflation, compounded monthly, so every figure is in today’s dollars. If you’re short, “extra a month” is the added contribution that would reach your FI number by the age you chose.

Treat it as a planning yardstick. Returns vary year to year, retiring well before 60 may call for a lower withdrawal rate (a bigger multiple), and taxes on withdrawals aren’t included.

Words you’ll see

FI number
The invested amount at which your portfolio could cover your spending indefinitely, making work optional.
4% rule
A rule of thumb for a sustainable first-year withdrawal from retirement savings. Its flip side is the 25× multiple.
Real return
Investment growth after subtracting inflation. Using it keeps every number in today’s dollars.
Employer match
Money your employer adds when you contribute to a workplace plan. Count it as part of your monthly contribution.

Common questions

What is an FI number?

Your FI (financial independence) number is the invested amount that could fund your spending indefinitely. The usual estimate is 25 times the yearly spending your savings must cover, which is the flip side of the 4% rule.

How much do I need to retire?

Take the yearly spending you expect in retirement, subtract income you will still receive such as Social Security or a pension, and multiply what is left by 25. If you will need $40,000 a year from savings, you need about $1,000,000.

Is the 4% rule still safe?

The 4% rule comes from historical U.S. market data, where a 4% first-year withdrawal, raised each year for inflation, lasted at least 30 years in most periods studied. It is a planning yardstick, not a guarantee. Retiring early, with a longer horizon, often calls for 3 to 3.5%.

Should I count Social Security in my FI number?

Yes. Subtract the yearly income you expect from Social Security, a pension or rentals before multiplying by 25, because your savings only have to cover the rest. Your personal Social Security estimate is at ssa.gov/myaccount.

Sources

  1. Determining Withdrawal Rates Using Historical Data, William P. Bengen, Journal of Financial Planning, 1994
  2. my Social Security: your personal Social Security account, U.S. Social Security Administration
  3. Compound Interest Calculator, U.S. Securities and Exchange Commission, Investor.gov

This tool is for informational and educational purposes only. It is not financial, tax, or legal advice. Consult a qualified professional for guidance specific to your situation.