Retirement Gap Calculator
How big is your retirement gap? Monthly need minus Social Security and other retirement income — plus the nest egg required (4% rule) and the monthly saving needed until retirement.
Key facts
- At the defaults ($5,000/month need, $2,082.76 Social Security — SSA average, May 2026) the gap is $2,917.24 per month. Under the 4% rule that takes a $875,172 nest egg at retirement — exactly 300× the monthly gap.
- Starting from the SCF median of $86,900 (account holders only — about 46% of US families have no retirement account at all), 6% nominal growth turns it into $437,344.62 over 27 years. Covering the remaining $437,827.38 takes saving $542.84 per month.
- Retirement age moves both sides: claiming Social Security at 62 instead of 67 (FRA for those born 1960+) permanently cuts the benefit by 30% ($1,000 → $700, SSA) — while also leaving 5 fewer years to save.
FAQ
- How is the retirement gap calculated?
- Monthly need in retirement minus your expected Social Security benefit minus other retirement income (pension, annuitized 401(k)/IRA). The gap sets the capital required: the annual gap divided by the withdrawal rate — under the 4% rule that is 300× the monthly gap. The saving rate is the monthly contribution that, together with today’s savings (compounded), reaches that capital by retirement.
- What is the 4% rule?
- A rule of thumb from Bengen’s 1994 study: withdrawing 4% of the portfolio in the first retirement year, then raising only with inflation, historically lasted 30 years with a 50/50 portfolio (S&P 500 / US Treasuries). Read in reverse: capital needed ≈ 25× the annual gap. It is a model value, not a guarantee — which is why the calculator lets you adjust the rate.
- How do I know my Social Security benefit?
- The default is the SSA average for retired workers ($2,082.76/month, May 2026). Your personal estimate is in your Social Security Statement at ssa.gov/myaccount — it depends on your earnings history and claiming age: claiming at 62 permanently cuts 30% at FRA 67, delaying to 70 increases the benefit.