Retirement Planner Spreadsheet: How Long Will It Last?

Picture a couple in their fifties sitting down on a Sunday afternoon with a pile of account statements. They know roughly what is in each pension and savings account, and they have a vague target in mind. What they cannot answer is the question that actually matters: if they stop working at the age they have in mind, how long will the money last? A retirement planner spreadsheet turns those scattered balances into a year-by-year picture, so the answer is a number you can see and adjust rather than a guess.

Below you will find a practical way to build your own retirement plan in a spreadsheet, plus a walk-through of the Retirement Planner Spreadsheet for Excel and Google Sheets if you would like the structure ready to fill in.

Get the Retirement Planner Spreadsheet →

Why a single nest-egg number is not enough

Most online calculators ask a few questions and return one figure: the amount you “need” by retirement. That figure is a starting point, but it leaves out most of what shapes a real plan:

• Two people, two timelines. Couples rarely share the same age, retirement date or income sources. A single-person calculator flattens that.
• Income does not stop at savings. State pensions or Social Security, workplace pensions, part-time work and rental income all start at different ages and change with inflation.
• Spending changes shape. Some costs drop when work stops, others go up. A plan that assumes today’s budget carries on unchanged can be off in either direction.
• Returns are uncertain. One projection at one rate of return gives a false sense of precision.

Scattered statements and one-off calculators cannot show all of that together. A spreadsheet can, as long as it is laid out well.

How to build a retirement plan in a spreadsheet

These steps work whether you use a template or start from a blank sheet:

1. Collect your inputs on one tab. Ages, the age you want to retire, the age you want to plan to, current balances by account, monthly saving and any employer match, expected annual raise, return rate, inflation and the withdrawal rate you want to test.
2. Write a retirement budget. List spending categories now and what you expect each to look like in retirement. This gives you a realistic yearly spending figure instead of a rule of thumb.
3. List income sources with start ages. Note who receives each one, when it begins and whether it rises with inflation.
4. Project year by year. One row per year: starting balance, contributions (until retirement), growth, income in, spending out, ending balance. Add a column that shows each year in today’s money so later numbers stay meaningful.
5. Find the “money lasts until” age. The first year the balance runs out is far more useful than a single target figure.
6. Run scenarios. Copy the projection with a cautious, an expected and a hopeful return rate. If the plan only works in the hopeful case, that tells you something.
7. Track real balances. Once a quarter, log actual account balances and compare them to the plan.

Tip: keep every assumption in one inputs tab and reference it everywhere. When you change inflation from one rate to another, the whole plan should update at once.

Common mistakes to avoid

• Mixing nominal and real numbers. A balance thirty years from now looks large until you convert it to today’s money. Show both, side by side, so you compare like with like.
• Forgetting the employer match. If your employer adds to your pension, include it as its own input. Leaving it out understates your saving.
• Assuming flat contributions. If your pay tends to rise, your saving usually does too. A raise percentage applied to contributions gives a fairer projection.
• Planning to an age that is too young. Choose a plan-to age that leaves a margin. Running out of money is a bigger problem than finishing with some left over.
• Setting it and never looking again. A plan is only useful if you update it. Once a year, refresh balances, returns and spending, and see whether the “money lasts until” age has moved.

Inside the Retirement Planner Spreadsheet

The Retirement Planner Spreadsheet ($3.99) is an .xlsx workbook for Microsoft Excel and Google Sheets, built with formulas only. It comes with a Setup Guide PDF and is designed for one or two people.

Start Here and My Numbers

Start Here explains the steps and how the maths works. My Numbers holds two ages, retire and plan-to ages, savings by account, monthly saving plus match, raise percentage, returns, inflation, withdrawal rate and spending.

Dashboard

The dashboard shows years to go, your nest egg, your target, an on-track percentage, the age the money lasts until, figures in today’s money, the extra monthly saving needed to close any gap, your first year of retirement and a chart.

Retirement Budget and Income Sources

The budget compares 18 categories now versus in retirement, with a chart, and feeds the plan. Income Sources covers Social Security or state pension, pensions, part-time work and rent, each with start ages and inflation, and income sources can be set by person.

Projection and Scenarios

Projection runs every year up to your plan-to age, with a today’s-money column. Scenarios puts cautious, expected and hopeful cases side by side with a chart, so you can see how sensitive your plan is to returns.

Savings Tracker and Checklist

The Savings Tracker logs real balances by account with a chart. The Checklist lists 20 jobs from now to retired, so the practical tasks sit next to the numbers.

Watch the setup guide and full tour

Here is a walk-through of setup and every tab:

Who it is for (and who it is not for)

A good fit if you:

• Want to plan retirement for yourself or as a couple, with separate ages and income sources
• Prefer seeing the “money lasts until” age rather than a single target number
• Like to test cautious and hopeful cases side by side
• Want a file you own and can revisit every year

Probably not a fit if you:

• Want personalised investment recommendations (this is a planning tool, not advice)
• Need detailed tax modelling for withdrawals from different account types
• Want balances to sync automatically from your bank or pension provider

Pair it with the Annual Budget Spreadsheet to get today’s spending clear first, or browse all spreadsheet templates.

FAQ

Does it work in Excel and Google Sheets?

Yes. Download the .xlsx file and open it in Excel. For Google Sheets, create a blank sheet, then File > Import > Upload > Replace spreadsheet.

Can I use it on my own, not as a couple?

Yes. It handles one or two people, so you can leave the second person’s details empty.

How accurate are the projections?

Projections are estimates based on the returns and inflation you type in. That is why the Scenarios tab exists: it shows how the plan changes under different assumptions.

Is it an instant download?

Yes. It is a digital download with the workbook and a Setup Guide PDF. Nothing physical is shipped.

Can I edit the budget categories?

Yes. It is your file, so you can rename categories and change any input. A computer is recommended for setup; the Google Sheets app works for quick updates.

This is a planning tool, not financial, tax or investment advice.

Get the Retirement Planner Spreadsheet →

Microsoft Excel is a trademark of Microsoft Corporation. Google Sheets is a trademark of Google LLC. This is an independent spreadsheet, not affiliated with or endorsed by Microsoft or Google.