Retirement Calculator Spreadsheet for Excel and Google Sheets

Most retirement calculators ask you for six numbers and hand back one: a target, usually somewhere north of a million dollars, with no explanation of where it came from or what would change it.

That number is useless on its own. What you actually need to know is whether the gap between where you’re heading and where you need to be is a rounding error or a crisis — and which of the three levers you control would close it fastest.

This guide builds that calculation from scratch. One household, run all the way through: the target, the projection, the gap, and what each lever is worth in dollars.

Every figure below is a worked example with my assumptions stated openly. Yours will differ. The structure is what transfers.

The Household We’ll Use

Dana is 42. Household income is $118,000. Current retirement savings across a 401(k), an old rollover IRA and a Roth: $214,000. Total going in each month, including the employer match: $1,100, or $13,200 a year — a savings rate of 11.2% of gross.

Target retirement age: 65.

Current household spending: $76,000 a year.

That’s every input. Everything from here is arithmetic.

Step 1: The Target Is Not 25× Your Current Spending

The famous rule of thumb is that you need 25 times your annual spending. Applied carelessly to Dana’s $76,000, that gives $1,900,000 and a sense of hopelessness.

Two corrections make it a real number.

Correction one: you won’t spend what you spend now. In retirement, the $13,200 going into retirement accounts stops. The mortgage is scheduled to be paid off. Commuting and work clothes drop. Health costs rise, and travel rises early on. Dana’s category-by-category estimate lands at $63,000 a year in today’s dollars.

Correction two: the portfolio doesn’t have to cover all of it. Dana’s SSA statement estimates a household benefit of about $34,000 a year starting at full retirement age. That’s income the portfolio never has to produce.

Twenty-five times the gap: $725,000.

Correction three, which most calculators skip entirely: the bridge. Dana wants to stop at 65, but the Social Security estimate assumes 67. For two years the portfolio covers the full $63,000, not the $29,000 gap. Two years × $34,000 of missing benefit ≈ $126,000 of extra portfolio needed.

$851,000, not $1,900,000. Same household, same spending, same rule of thumb — the difference is entirely in netting out Social Security and pricing the bridge separately. (The 25× multiplier itself, and where it comes from, is explained here.)

Step 2: The Projection

Twenty-three years of compounding on $214,000, plus $13,200 a year.

Work in real returns — after inflation — and keep everything in today’s dollars. It’s the single best simplification in retirement math, because it means the answer comes out in money you can actually picture. A 4.5% real return is a reasonable middle assumption for a stock-heavy portfolio.

Growth of what’s already there: $214,000 × 1.045²³ = $588,966

Growth of future contributions: $13,200 × [(1.045²³ − 1) ÷ 0.045] = $513,972

Projected at 65: $1,102,938

Against a target of $851,000, Dana is on track with roughly $252,000 of cushion.

That’s the headline. It is also the least useful number in this guide, because it’s a single point estimate resting entirely on one assumption.

Step 3: The Only Question That Matters — What If I’m Wrong?

Run the same projection at three real returns:

Look at what a 1.5-point return miss does. It doesn’t reduce the cushion — it deletes it. At 3% real, Dana arrives at 65 with the exact minimum and no margin for a bad first decade, a roof, or a spending estimate that was optimistic.

This is why a scenario table is not a nice-to-have. A single-column calculator would have told Dana “on track, $252k spare” and left her structurally exposed to an outcome that is nowhere near a worst case. Three percent real is an ordinary, unremarkable stretch of market history.

Step 4: What Each Lever Is Worth

Three things are actually under Dana’s control. Here’s what each buys, at the 4.5% expected case:

Save $300 more a month. $3,600 a year × 38.94 (the 23-year annuity factor) = +$140,174.

Work two more years, to 67. Contributions compound two extra years and the bridge disappears — Social Security now starts the year she stops.

Two years of work doubles the cushion, because it moves both sides of the equation at once. This is the most underrated fact in retirement planning and the reason “just retire a year later” is such a powerful lever compared to “just save more.”

Cut $200 a month from retirement spending. $2,400 a year off the gap × 25 = $60,000 off the target, permanently, with no extra saving at all. Every dollar of recurring retirement spending you can design out is worth twenty-five dollars you don’t have to accumulate.

Rank them: two more years > $300/month more saved > $200/month less spent. That ranking is specific to Dana’s numbers. Run it on yours and the order can flip — which is exactly why it’s worth running.

Step 5: Where the Money Should Go

The projection assumes $13,200 a year gets invested. It says nothing about where, and that choice is worth real money in tax.

For 2026 the ceilings are $24,500 in a 401(k), 403(b), governmental 457 or the TSP, with an $8,000 catch-up at 50+ and an $11,250 catch-up for people turning 60 through 63, and $7,500 in an IRA with a $1,100 catch-up. HSAs allow $4,400 self-only and $8,750 for family coverage, plus $1,000 if you’re 55 or older.

The order you fill them in changes the outcome more than most people expect — an employer match is an instant, guaranteed return no market assumption can compete with. The full funding order, with a worked allocation, is here.

Step 6: The Spending Side, Category by Category

The $63,000 estimate deserves more than a single line, because it’s the input the entire target is built on and the one people guess at most casually.

Build it as a table, not a number. Housing, healthcare, food, transport, insurance, travel, gifts, everything else — with today’s cost, an expected retirement cost, and a note on why they differ.

Two things fall out of building it this way. Healthcare more than doubles, and the years between retiring and Medicare eligibility at 65 are where that bites hardest — a real argument against retiring at 60 on a thin margin. And travel is front-loaded: most people spend more in their first retirement decade than their third, which means a flat annual spending assumption quietly overstates the late years and understates the early ones.

Step 7: Getting the Money Out

The target answers “how much.” A withdrawal plan answers “how much a year, and in what order.”

The 4% rule gets Dana from a $851,000 balance to roughly $34,000 of first-year withdrawal capacity, comfortably above the $29,000 gap. But a fixed percentage of a moving balance behaves very differently depending on when the bad years arrive — a 20% drop in year one is a far worse event than the same drop in year fifteen, even though the average return is identical.

There are also withdrawals you don’t choose: required minimum distributions begin at age 73 for most people retiring now, rising to 75 for later cohorts under SECURE 2.0, and they’re calculated on your traditional balance whether you need the money or not. The full withdrawal analysis, including what a safe rate really looks like, is here.

Step 8: The Social Security Decision

The $34,000 estimate assumes claiming at full retirement age. Claiming early or late changes it substantially and permanently: with a full retirement age of 67, claiming at 62 cuts the benefit by 30%, and delaying to 70 raises it by 24%.

For Dana’s $34,000, that’s a spread from about $23,800 to about $42,160 a year — a $18,360 annual difference that reshapes the portfolio target on its own. The break-even math for 62 versus 67 versus 70 is here.

If You Want to Retire Well Before 65

Everything above assumes a conventional timeline. If the goal is to stop at 50 or 55, the math changes shape: Social Security is decades away, the bridge isn’t two years but fifteen, and your savings rate becomes far more important than your return assumption. The financial independence version of this calculation is here.

The Eight Numbers to Track

Everything in this guide comes from a short list. If you build nothing else, build this:

1. Current age and target retirement age
2. Current total retirement balance
3. Annual contributions, including employer match
4. Estimated retirement spending, built by category
5. Estimated Social Security, from your own SSA statement, with the age it assumes
6. Real return assumptions — three of them, not one
7. The gap: spending minus guaranteed income
8. The bridge: years between retiring and benefits starting

Update it once a year, in the same month, with actual balances. The value isn’t in the projection being right — it won’t be. The value is in watching the gap between projection and target move, and knowing a year early when it’s moving the wrong way.

Dana’s plan works. It works with $252,000 to spare in the expected case and with nothing to spare in a mildly disappointing one. That’s a useful thing to know at 42, when two more years of saving or a $200 trim to a future spending category can still fix it — and a useless thing to discover at 64.

Featured on ReadySheetGo

Retirement & FIRE Calculator — 9 tabs and 463 working formulas built around exactly this workflow. A single Your Info tab collects every input in yellow-highlighted cells; a Dashboard returns an ON TRACK / NEEDS ATTENTION readiness status; a Savings Projection tab runs 40 years of compound growth with a portfolio chart; an Account Planner optimises contributions across 401(k), Traditional IRA, Roth IRA, HSA and brokerage with a recommended funding order; a FIRE Calculator returns your independence number, years to FIRE and progress percentage with a savings-rate scenario table; a Withdrawal Strategy tab covers the 4% rule, an RMD schedule for ages 73–90 and a tax-efficient withdrawal order; an Expense Planner projects retirement spending by category with inflation adjustment; and a Scenarios tab runs best, expected and worst case side by side with a Social Security claiming comparison at 62, 65, 67 and 70. Dual-income support for couples. Formula cells protected. Works in Excel and Google Sheets, no macros. Instant digital download — $17.99.