How much do you need to retire? A step-by-step way to estimate it

There is no single magic number for retirement. The right amount depends on how you want to live, where you live, what other income you will have, and how long you will need the money. A simple, repeatable method gives you a figure to work toward and to adjust as your life changes. This guide takes you through it step by step, with an example.

Why common shortcuts fall short

You may have seen rules such as "replace 70 to 80% of your final salary" or "save ten times your income." They are convenient, but they are generic. Someone who owns their home outright and travels little needs a very different amount from someone who rents in an expensive city and plans to travel. Starting from your own expected spending gives a more useful answer.

Step 1: estimate your spending

Look at what you spend now and think about what will change. Group costs into broad categories.

• Essentials: housing, food, utilities, insurance, transport, healthcare and taxes.
• Lifestyle: travel, hobbies, dining out, gifts and entertainment.
• Irregular costs: home repairs, vehicle replacement, medical procedures and supporting family.

Some costs may fall in retirement, such as commuting, work clothes and perhaps the mortgage. Others may rise, particularly healthcare and leisure in the early years. Add a margin for the unexpected, since actual costs often exceed estimates.

Step 2: subtract other income

If you expect a pension, a state benefit, rental income or part-time earnings, subtract the yearly amount from your spending. What remains is the gap your own investments must fill.

An example. If you expect to spend 45,000 a year and will receive 15,000 a year from a pension and state benefit, the gap is 30,000.

Step 3: apply a withdrawal rate

Divide the gap by a withdrawal rate to find your target portfolio.

• At 4%, the target is about 750,000 (30,000 divided by 0.04, or 25 times).
• At 3.5%, about 857,000.
• At 3%, 1,000,000.

A lower rate is more cautious and suits a longer retirement. A higher one needs less capital but leaves less margin for poor markets. The 4% figure comes from historical research and is a starting point, not a promise.

Step 4: allow for inflation

Prices will rise between now and retirement, and during it. If you are 20 years from retirement and expect 3% inflation, today's 45,000 of spending would be about 81,000 in future money. Make sure you either plan in today's money consistently, using returns after inflation, or inflate your costs. Mixing the two is a common source of error.

Step 5: stress-test the plan

Ask what would happen if things turned out worse than expected.

• Inflation higher than planned. Does the plan still work?
• Weak returns early on. A poor first few years can do disproportionate damage. Could you cut spending or use a cash reserve?
• Living longer. Would the money last into your nineties?
• Higher healthcare or care costs. Do you have insurance or a buffer?
• A major event, such as a divorce, a dependent's needs or a period without income.

You can test these by lowering your assumed return, raising your spending by 10 to 20%, and extending your retirement by five or ten years, then seeing whether the target still looks reachable.

Step 6: work out how to get there

Once you have a target, calculate what you must save. Take your current savings, your timeline and an assumed return after inflation, and work out the monthly amount. Online calculators can help, and a spreadsheet makes it easy to experiment. If the monthly figure is too high, you can adjust the three levers: save more, work longer, or plan for lower spending.

Things people often forget

• Taxes on withdrawals, which differ by account type and country.
• The cost of long-term care late in life.
• Support for children or parents.
• Fees on investments, which reduce your effective returns.
• A partner's needs, including if one of you outlives the other.

Common mistakes

• Using today's salary as a stand-in for retirement spending.
• Ignoring inflation or mixing real and nominal figures.
• Assuming high returns without a margin.
• Forgetting taxes, care costs and fees.
• Making a plan once and never revisiting it.

A short checklist

• I have estimated my retirement spending by category.
• I have subtracted pensions and other income to find the gap.
• I have chosen a withdrawal rate and tested a cautious one.
• I have stress-tested for inflation, weak returns and longevity.
• I will update the plan every year.

Treat the result as a range and not a promise. If your situation is complex, a qualified planner who knows the rules in your country can refine it.