How this retirement calculator works
Enter your age, the age you'd like to retire, your current savings, how much you add each month and an expected return after inflation. The calculator grows your savings month by month until retirement to project your nest egg in today's dollars.
It then applies the 4% rule: withdrawing 4% of the starting balance in the first year, adjusted for inflation after that, has historically lasted about 30 years in most US market periods. Your sustainable monthly income is 4% of the nest egg divided by 12, plus any Social Security you enter.
To judge whether you're on track, the calculator compares that income with your planned spending. If there's a shortfall, it works out the exact extra monthly contribution that would close the gap by your retirement date. Use the What if sliders to see how saving more, retiring later or spending less changes the picture.
The math behind the projection
The projection and the gap use standard future-value math with the 4% rule:
Nest egg = S(1 + i)^m + C × [ (1 + i)^m − 1 ] ÷ i Target = (spending − Social Security) × 12 ÷ 0.04
- S = current savings; C = monthly contribution
- i = monthly real return; m = months until retirement
- Gap = Target − Nest egg
- Extra monthly saving = Gap × i ÷ [ (1 + i)^m − 1 ]
Worked example
A 35-year-old with $60,000 saved who invests $800 a month at a 5% real return until 67 would have roughly $1.05 million in today's dollars. Under the 4% rule that supports about $3,510 a month; with $1,900 from Social Security, total income is about $5,410.
If they plan to spend $6,000 a month, they need about $1.23 million — a shortfall of roughly $178,000. Saving about $188 more each month closes it. Retiring at 69 instead shrinks the gap to about $47,000, which needs only around $44 a month more.
How much do you need to retire?
A popular shortcut is to multiply the yearly spending your savings must cover by 25. That's the 4% rule in reverse: a portfolio 25 times your annual withdrawals can sustain 4% a year. Subtract the income you'll get from Social Security or a pension first, because those reduce what your savings must provide.
Your number depends on lifestyle more than salary. Housing paid off, lower commuting costs and the end of retirement contributions often reduce spending; health care, travel and long-term care can raise it. Planning for 70% to 80% of current spending is a common starting point, but a line-by-line retirement budget is better.
Understanding the 4% rule
The 4% rule comes from studies of historical US stock and bond returns, which found that a balanced portfolio withdrawn at 4% of its starting value, adjusted for inflation each year, survived 30-year retirements in most historical periods. It's a planning guideline, not a guarantee.
If you retire early, expect a retirement longer than 30 years, or want extra safety, a 3.25% to 3.5% rate is more conservative. Flexible spending — cutting back slightly after poor market years — also improves the odds considerably.
Social Security's role
For most Americans, Social Security replaces a meaningful share of pre-retirement income, and it's adjusted for inflation each year. Your benefit depends on your 35 highest-earning years and the age you claim. Claiming at 62 permanently reduces your benefit; delaying past full retirement age, up to 70, raises it by 8% for each year you wait.
Get your personalized estimate from your my Social Security account at ssa.gov and enter it here. If you're decades from retirement and want to be conservative, you might enter a reduced figure.
If you're behind
Being behind is common and fixable. The four levers are saving more, working longer, investing appropriately and spending less in retirement. Working two or three extra years is unusually powerful: you contribute longer, your savings compound longer, you draw on them for fewer years and your Social Security benefit grows.
Capture any employer match first — it's an immediate return on your money. After age 50, catch-up contributions let you put extra into a 401(k) and IRA. Increasing your contribution by 1 percentage point each year, especially when you get a raise, closes gaps without a painful budget cut.
Assumptions to revisit
This calculator works in today's dollars using a real return, so there's no need to inflate your spending target. It assumes a steady return; real markets fluctuate, and poor returns just before or after you retire matter most. It also ignores taxes on withdrawals: money in a traditional 401(k) or IRA is taxed as income when withdrawn, so you may need more savings to net the same spending. Revisit your plan once a year and after any major life change.
Frequently asked questions
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Not financial advice. ClearCalc provides estimates for educational purposes only. Results depend on the assumptions you enter and may differ from offers from lenders or institutions. Consult a qualified professional before making financial decisions.