Retirement Gap Calculator
Identify the gap between your projected retirement savings and your income goal.
What this calculator does
This calculator measures the distance between the retirement you want and the retirement your current savings are on course to deliver. It converts your target monthly income, less any Social Security or pension you expect, into the nest egg that income requires at a 4 percent withdrawal rate, then projects what your existing savings grow into with no further contributions.
The difference between those two figures is your gap, and the calculator converts it into the monthly saving needed to close it by your retirement date. That final number is the whole point: a gap expressed as a lump sum is intimidating, while the same gap expressed as a monthly contribution is a decision.
When to use it
It is most useful as an annual checkpoint, run alongside your Social Security statement and your plan balances. Unlike a projection calculator, which tells you where you are heading, this one tells you how far off course you are and what it costs per month to correct.
It also frames trade-offs unusually well. Because the required nest egg is driven by the income gap rather than total income, you can immediately see what claiming Social Security at 70 instead of 62 does, or what trimming $500 a month from your expected retirement spending is worth in capital. Both often beat saving harder.
Understanding the inputs
Target monthly income should be what you expect to spend, not what you earn now. A common starting point is 70 to 80 percent of current income, though anyone planning to retire before Medicare eligibility at 65 should add several hundred dollars a month for health insurance premiums bought on the open market.
Projected pension is where Social Security goes, and it deserves an accurate figure rather than a guess, because a 4 percent rate turns each monthly dollar into 300 dollars of required capital. Current savings should cover all retirement accounts. Years to retirement drives the compounding, and expected return should be conservative if that number is small.
How is this calculated?
Required Nest Egg = (Target − Pension) × 12 / 0.04. Gap = Required − Projected FV of Current Savings.
A worked example
Someone wanting $7,000 a month with $2,200 expected from Social Security has a $4,800 monthly gap. At a 4 percent withdrawal rate that requires a nest egg of $1,440,000. With $250,000 saved, 20 years to go, and a 6 percent return, the existing balance grows to roughly $802,000 on its own.
That leaves a gap of about $638,000, which needs roughly $1,381 a month of new saving at 6 percent to close. Note what Social Security is doing here: without it, the required nest egg would be $2,100,000 rather than $1,440,000, a difference of $660,000 in capital.
Limitations and assumptions
This is a projection under fixed assumptions rather than a prediction. It applies one constant return, ignores taxes on withdrawals entirely, and treats a 4 percent withdrawal rate as safe when its historical basis is a 30-year retirement with a specific asset mix. Retire early or live long and that rate is optimistic.
It also works in nominal dollars against a target expressed in today's money, so long horizons understate the gap unless you enter a real return. And sequence-of-returns risk means the actual balance you arrive with could differ substantially from the projection even if the average return proves exactly right. Treat the gap as a direction, not a measurement.
Common Questions
- What exactly is the retirement gap?
- It is the shortfall between the nest egg your target income requires and the nest egg your current savings are projected to grow into on their own. The calculator sizes the requirement from your income goal minus expected Social Security, then subtracts a projection of what you already hold with no further contributions.
- Why does the baseline exclude future contributions?
- Deliberately, so the gap represents new saving you have not yet committed to. If contributions were built into the baseline the gap would shrink to reflect a plan you may not follow. Starting from what happens if you stop saving today makes the required monthly figure the actionable output.
- What should I put for projected pension?
- For most US households this is Social Security. The average retired worker receives a little over $1,900 a month; your own estimate is on your ssa.gov statement. Add any traditional employer pension or annuity income. Every dollar entered here removes 300 dollars from the required nest egg at a 4 percent rate.
- Why is the required nest egg so large?
- Because a 4 percent withdrawal rate means every dollar of monthly income needs 300 dollars of capital behind it. A $1,000 a month gap requires $300,000. That multiplier is what makes Social Security so valuable and why closing even a few hundred dollars of monthly gap has an outsized effect.
- The monthly savings figure looks impossible. Now what?
- Attack the requirement rather than the contribution. Lowering your target income, delaying retirement by three years, or claiming Social Security at 70 instead of 62 all shrink the gap before you save an extra dollar. Delaying benefits to 70 raises them by 24 percent over the full retirement age amount.
- Does this account for inflation?
- Not directly. The target income you enter is in today's dollars and the projection is in nominal dollars, which understates the gap over long horizons. A practical fix is to lower your expected return by your inflation assumption, turning it into a real return, so the whole calculation sits in today's money.
- Should home equity count as current savings?
- Generally no, unless you have a firm plan to downsize and can name the amount released. A house you live in produces no income and cannot be drawn from at 4 percent a year. Reverse mortgages and HELOCs exist but carry costs that make them a fallback rather than a retirement plan.
- What return should the projection use?
- Six to seven percent nominal for a stock-heavy portfolio, less as you approach retirement and shift toward bonds. If you are within ten years of retiring, using 7 percent will flatter the projection and understate your gap, which is the more dangerous direction to be wrong in.
- How often should I recheck the gap?
- Annually, and after any major change: a raise, a job move, a new Social Security estimate, or a change in what you expect to spend. The gap moves with all of them. What you want to see year over year is the required monthly savings figure falling rather than the projected balance rising.