Retirement Savings Calculator
Check your projected retirement balance against a real spending target using the 4% rule, with the gap and the monthly savings that would close it.
Today's dollars.
4% is Bengen's original rule of thumb.
Target balance
$1,750,000.00
Projected balance
$1,462,966.65
Gap to target
$287,033.35
Monthly savings needed
$1,035
Not yet on track: closing the gap by retirement needs about $1,035/month in total (not just the extra) at this return, starting now.
How it's calculated
The target is your annual spending divided by your withdrawal rate -- at the default 4%, that's spending times 25 (William Bengen, 1994, Journal of Financial Planning):
target = annual spending ÷ withdrawal rate
Your projected balance uses the same growth engine as every calculator on this site: current savings compounded monthly, plus your monthly contribution as an ordinary annuity. The monthly savings needed solves that same formula backward for the payment that closes any remaining gap by retirement.
Worked example
The calculator's own defaults: age 35, retiring at 65, $60,000 saved, $800/month going in, 7% expected return, $70,000/yr planned spending.
| Target (25x spending) | $1,750,000.00 |
| Projected balance at 65 | $1,462,966.65 |
| Gap | $287,033.35 |
Frequently Asked Questions
What is the 4% rule, really?
A rule of thumb, not a guarantee: William Bengen's 1994 study ("Determining Withdrawal Rates Using Historical Data," Journal of Financial Planning) found a 4% initial withdrawal rate, increased with inflation every year after, survived every rolling 30-year period in the historical U.S. market data he tested. It sets a target balance of 25 times your annual spending. Later research (the "Trinity Study" and others) has both supported and challenged the exact number under different market and time-horizon assumptions -- treat it as a reasonable starting point, not a law of nature.
Why 25 times spending?
It's the same 4% rule stated as a multiple instead of a rate: withdrawing 4% a year means the balance is 25x that annual amount (spending ÷ 0.04 = spending × 25). Lower your withdrawal rate input and the multiple rises -- 3% implies a 33x target, a more conservative bar for a longer or less certain retirement.
What if I don't know my future spending?
A common shortcut is a replacement ratio: 70-80% of your pre-retirement income is a frequently cited starting range, since some costs (commuting, retirement saving itself, payroll taxes) drop away. Multiply your current income by that percentage and use it as the annual spending figure here.
Is the monthly savings figure the extra I need, or the total?
The total. If you're currently saving less than the figure shown, the difference is what to add; if you're already saving more, you're ahead of what the 4% rule alone requires.
Does this account for Social Security?
No -- it assumes your entire retirement spending comes from the balance you're projecting here. If you expect meaningful Social Security or pension income, your real target balance is lower: subtract that income's approximate present value, or simply reduce the annual spending figure you enter by your expected annual benefit.
Figures on this page are estimates from the inputs you enter, not financial advice, and this site is not affiliated with any employer, plan administrator, bank or the IRS. Real accounts vary by plan rules, taxes and fees this tool doesn't model -- see the Terms.