Retirement Income Gap Calculator

Retirement Income Gap: At a Glance

Two income buckets

Retirement income splits into guaranteed income (Social Security, pensions, other steady income) and portfolio withdrawals. This calculator adds them together and checks the total against your spending.

The withdrawal rate matters

How much your portfolio can safely produce each month depends on the rate you assume. Morningstar’s own guidance for 2026 puts a sustainable starting rate at 3.9%, up from 3.7% the year before.

A gap isn’t a verdict

A shortfall points to specific levers — delaying Social Security, trimming expenses, adjusting the withdrawal rate, or working part-time — not an unsolvable problem.

Guaranteed income is the foundation

The larger the share of your expenses covered by guaranteed income, the less your plan depends on markets cooperating.

How Your Income Gap Is Calculated

This calculator compares two totals every month: what you can count on, and what you plan to spend.

Guaranteed monthly income = Social Security + pension + other steady income (part-time work, rental income, annuity payments).
Portfolio monthly income = your total portfolio balance × withdrawal rate ÷ 12.
Total available income = guaranteed income + portfolio income.
Your gap or surplus = monthly expenses − total available income.

The withdrawal rate you choose drives a large share of the result. The calculator above offers 3.5%, 4%, and 4.5% as starting points — a lower rate is more conservative (your portfolio is less likely to run dry over a long retirement), a higher rate produces more income now at greater long-term risk. For context, Morningstar’s most recent research puts a sustainable starting withdrawal rate at 3.9% for 2026, based on a 30-year time horizon, a 30–50% equity allocation, and a 90% success target — and that figure moves most years as market conditions change, so it is worth treating as a benchmark rather than a fixed rule.

A Worked Example

Say you’re looking at $2,200 a month from Social Security, no pension, and $300 a month from a small rental property. Monthly expenses run $5,200. Your portfolio is $600,000, and you use the standard 4% withdrawal rate.

	Monthly Amount
Guaranteed income (SS + other)	$2,500
Portfolio income ($600,000 × 4% ÷ 12)	$2,000
Total available income	$4,500
Expenses	$5,200
Gap	–$700/mo (86.5% covered)

That $700 monthly shortfall is real, but it is not fixed. Two ways it could close, using tools already covered elsewhere on this site:

Delay Social Security a few years and the benefit itself grows — waiting from 67 to 70 raises it by roughly 24%, taking that $2,200 to about $2,728 and cutting the gap to under $200 a month. (See the Social Security Claiming Age Calculator for the exact math.)
Trim $700 a month from expenses — about 13.5% of the $5,200 budget — and the gap closes completely at the same withdrawal rate.

This example uses round numbers to show the mechanics. Your own guaranteed income, portfolio size, and spending will change the result — use the calculator above with your actual figures.

What Actually Decides Whether a Gap Is a Problem

Two households with the identical dollar gap can be in very different positions. What matters beyond the raw number:

Sequence-of-returns risk

A portfolio that loses value in the first few years of withdrawals is under far more strain than the same average return spread evenly over a retirement. A gap that looks manageable on paper can turn serious if a downturn hits early.

How much flexibility your expenses actually have

A budget built entirely from fixed costs — housing, insurance, debt — has nowhere to give in a bad year. A budget with real discretionary spending (travel, dining out) has a lever most retirees underuse: temporarily spending less when markets are down.

What this calculator doesn’t count

Home equity, an expected inheritance, a paid-off mortgage, or planned part-time income can all offset a gap without showing up in the numbers above. None of them should be treated as guaranteed until they actually materialize.

How much of your income is guaranteed

A household covering 80% of expenses from Social Security and a pension can tolerate a rough market far better than one covering 20% the same way — even with an identical total income. Guaranteed income doesn’t fluctuate with the market; portfolio income does.

The planning horizon you chose

Planning to 85 versus 95 changes how aggressive a withdrawal rate looks. Given the real chance of living longer than average, erring toward a longer horizon is usually the more conservative choice.

Common Mistakes

Using today’s spending as the retirement number without adjusting for healthcare, travel, or decades of inflation.
Treating the withdrawal rate as fixed regardless of how markets perform, with no plan to spend less in a down year.
Assuming part-time income or a side business will last as long as the plan needs it to.
Never stress-testing a lower withdrawal rate or an early bear market against the same numbers.
Treating any gap as a verdict rather than a starting point for a short list of specific, solvable adjustments.

Frequently Asked Questions About the Retirement Income Gap

What counts as “guaranteed income” in this calculator?

Social Security, pension payments, and any other income you can count on regardless of market performance — an annuity payment, for example. Part-time work is included as “other income,” though it’s worth treating as less certain than the rest.

Where does the 4% withdrawal rate come from?

It traces back to financial planner William Bengen’s 1994 research, which tested historical market returns to find a starting withdrawal rate that would have survived a 30-year retirement in nearly every historical period. It became the industry’s default reference point, though not a guarantee.

Is 4% still considered safe today?

It depends who you ask and which year’s research you’re reading. Morningstar’s own updated guidance for 2026 puts a sustainable starting rate at 3.9%, versus 3.7% the year before — the number moves with capital market assumptions, so treat any single figure as a benchmark, not a law.

What if I use a more conservative 3.5% rate instead?

Your projected portfolio income drops, which widens any gap — but it also means your portfolio is less likely to be depleted over a long retirement. It’s a real trade-off between income today and safety margin later, not a free choice.

What if I have a pension — how does that change things?

A pension counts as guaranteed income alongside Social Security, which typically shrinks or eliminates the portion of your expenses that depends on portfolio withdrawals — and reduces how much your plan depends on market performance.

Does this calculator account for inflation?

Not automatically — it works off the numbers you enter today. Revisit it periodically and update your expense and income figures rather than assuming a single calculation holds for a 20- or 30-year retirement.

What if my expenses will change significantly in retirement?

Run the numbers with your best estimate of retirement-specific spending — healthcare and travel often rise, commuting and retirement-account contributions disappear — rather than your current working-years budget.

I have a gap — what are my realistic options?

In rough order of how directly they help: delay claiming Social Security if you haven’t yet, trim discretionary expenses, work part-time for a few years, or accept a somewhat higher withdrawal rate with the added risk that comes with it.

Does delaying Social Security actually help close a gap?

Often significantly — delayed retirement credits add about 8% a year up to age 70. See the Social Security Claiming Age Calculator on this site for the exact numbers at your own birth year and benefit.

Should I count home equity or an expected inheritance in my portfolio balance?

Generally no, not as spendable income unless you have a concrete plan to convert it — downsizing, a reverse mortgage, a formal inheritance already in probate. Treat these as a backup margin, not part of the baseline calculation.

Does my portfolio’s investment mix change this math?

Yes, indirectly. A more conservative portfolio (heavier in bonds and cash) typically supports a lower sustainable withdrawal rate than a more growth-oriented one, since it has less long-term growth to offset ongoing withdrawals — Morningstar’s figures assume a 30–50% equity allocation.

Does this calculator account for taxes on withdrawals?

No — it compares gross income to gross expenses. Withdrawals from a traditional IRA or 401(k) are generally taxable, so your after-tax income will be somewhat lower than the totals shown here.

What is “coverage percentage,” and why does it matter beyond the dollar gap?

It’s your total available income as a percentage of expenses. Two households with the same dollar gap can have very different coverage percentages depending on how large their expenses are — it’s a useful second lens on the same problem.

What if I plan to work part-time in retirement?

Include the expected income under “other income,” but consider running the numbers again without it — part-time work plans don’t always last as long as intended, whether by choice or circumstance.

How often should I re-run this calculation?

At least once a year, and any time something changes materially — a new Social Security claiming decision, a market downturn, a change in your spending, or a pension starting or ending.

Is this a substitute for professional advice?

No. It’s an educational planning tool meant to show the shape of the trade-off between guaranteed income, portfolio withdrawals, and spending. For an actual retirement income plan, verify your numbers with a qualified financial professional.

Sources & References

Educational use only. This page reflects retirement-income research and federal rules in effect as of September 2026 and is not personalized financial, legal, or tax advice. Always verify your own figures with a qualified financial professional.

About the Author

Susan Delaney is the founder of Essential Retirement Guide and the author of retirement planning resources covering Social Security, retirement taxes, IRAs, and retirement income planning.

Essential Retirement Guide creates educational tools designed to make complex retirement planning topics easier to understand and use.

The information and calculators on this website are reviewed and updated to reflect current federal retirement and tax rules. Always verify your individual circumstances with a qualified financial professional before making important financial decisions.