Mid-career
- Input
- £30,000/year spend, 25 years, 3% inflation
- Output
- Corpus £1.57m · about £750k in today's money
The nominal figure looks daunting but is inflated across 25 years. The real figure is the meaningful comparison.
Retirement Calculator
A retirement calculator estimates the sum needed to stop working and what must be saved to reach it. Two adjustments decide whether the answer is meaningful: inflating today's expenses to what they will cost at retirement, and then discounting the resulting corpus back to today's money so the number means something. Calculators that do only the first produce figures that sound alarming but are not comparable to anything.
Runs entirely in your browser — your figures are never uploaded.
How much do I need to retire?
The corpus needed is your annual expense at retirement divided by a sustainable withdrawal rate. Spending £30,000 a year today, retiring in 25 years with 3% inflation, means £62,800 a year then — needing roughly £1.57 million at a 4% withdrawal rate.
This is a projection tool, not financial advice. Retirement planning depends on personal circumstances, tax and market conditions — consult a qualified adviser before acting on any figure.
years
years
£
Living costs, not income
£
%
%
%
4% is the common rule of thumb
Corpus needed at retirement
£1,570,333
worth about £750,000 in today's money
- Spending at retirement
- £62,813
- Savings will grow to
- £367,009
- Shortfall
- £1,203,325
- Save each month
- £1,257
£30,000 today after 25 years of 3% inflation
for 25 years
The headline figure is in future money, which is why it looks large. In today's terms the target is £750,000. Dropping the withdrawal rate from 4% to 3% would raise the corpus needed by about a third — the assumption matters as much as the saving.
The maths
Retirement Calculator formula
Formula
Future expense = Current expense × (1 + inflation)^years · Corpus = Future annual expense / withdrawal rate
- Current expense
- What you spend each year today
- inflation
- Expected annual inflation as a decimal
- years
- Years until retirement
- withdrawal rate
- Sustainable annual withdrawal, often taken as 4%
Worked example
Spending £30,000 a year today, retiring in 25 years, 3% inflation
Inputs
- Current annual expense
- £30,000
- Years to retirement
- 25
- Inflation
- 3%
- Withdrawal rate
- 4%
Working
- Future expense = 30,000 × 1.03^25 = 30,000 × 2.0938 = £62,813
- Corpus = 62,813 ÷ 0.04
About £1,570,000 at retirement. In today's money that is worth roughly £750,000.
How to
How to use the Retirement Calculator
- 1
Enter your current spending
Use annual living costs today, not income. Retirement spending is often 70–80% of working spending once commuting and saving stop.
- 2
Set your timeline
Enter your age and intended retirement age. The gap drives everything, because it determines how long compounding has to work.
- 3
Choose inflation and withdrawal assumptions
3% inflation and a 4% withdrawal rate are common starting points. Both are assumptions, and the result is sensitive to each.
- 4
Read the monthly saving
The calculator shows what you need to save each month given what you already have. Check the today's-money figure to sense-check the target.
Examples
Retirement Calculator examples
Starting ten years later
- Input
- Same target, 15 years instead of 25
- Output
- Monthly saving roughly triples
Ten fewer years removes the compounding that does most of the work, which is why starting early matters more than saving more.
A more cautious withdrawal rate
- Input
- Same inputs at 3% withdrawal
- Output
- Corpus £2.09m
Dropping the withdrawal rate from 4% to 3% raises the corpus needed by a third. The assumption matters as much as the saving.
Why use it
What the Retirement Calculator gives you
Inflation applied on both sides
Expenses are inflated to retirement and the corpus is discounted back, so the target can be judged against what money is worth today.
The withdrawal rate is visible
Exposed as an input rather than hidden, because moving it from 4% to 3% changes the answer by a third.
Existing savings counted
What you already have compounds toward the target, reducing the monthly figure accordingly.
Entirely private
Retirement plans and balances never leave your browser.
Good to know
Retirement Calculator limitations
- Assumes a constant return and constant inflation. Neither holds, and a poor sequence of returns early in retirement is the largest single risk.
- The 4% rule derives from US market history over 30-year retirements and may not hold for other markets or longer retirements.
- State pensions, employer schemes and other income sources are not included and would reduce the corpus required.
- Healthcare costs typically rise faster than general inflation, which a single inflation rate does not capture.
Summary
Retirement Calculator in short
- Corpus = future annual expense ÷ withdrawal rate.
- Inflate today's spending to retirement before dividing.
- £30,000 a year today becomes £62,813 after 25 years at 3%.
- Moving the withdrawal rate from 4% to 3% raises the target by a third.
- Starting ten years earlier matters more than saving more each month.
FAQ
Retirement Calculator questions
How is the retirement corpus figure worked out?
Divide your expected annual spending at retirement by a sustainable withdrawal rate. Spending £62,813 a year at a 4% rate requires about £1.57 million. The figure is only as good as those two assumptions.
What is the 4% rule?
A guideline that withdrawing 4% of a portfolio in the first year, rising with inflation, historically lasted 30 years in US markets. It is a starting point, not a guarantee, and assumes a particular asset mix.
Why does inflation matter so much?
Because it compounds over decades. At 3%, costs double roughly every 24 years, so £30,000 of spending today becomes £62,813 in 25 years. Ignoring it understates the target by more than half.
When should I start saving?
As early as possible, because compounding does most of the work in the final years and those years only exist if the money is invested early. Delaying ten years can roughly triple the monthly saving required.
Will I spend the same in retirement?
Usually less — commuting, saving and often a mortgage all stop. A common estimate is 70–80% of working expenditure, though healthcare costs tend to rise in later retirement and can reverse the pattern.
Should I include a state pension?
Yes, if you expect one. Subtract the annual amount from your spending before calculating the corpus, since that portion does not need to come from savings. This can reduce the target substantially.
What if I cannot save the amount shown?
The main levers are retiring later, spending less in retirement, or saving more. Retiring two years later helps twice over: the corpus grows longer and needs to last a shorter period.
What growth rate should I use for the accumulation years?
Conservative is safer. A real return of 4–5% above inflation is a common long-run equity assumption, but assuming a high rate produces a comfortable projection and an uncomfortable retirement.
Is my retirement data uploaded?
No. Every figure is computed in your browser. Income, savings and retirement plans are among the most sensitive data there is, and none of it is transmitted or stored.
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