From first deposit
to your last paycheck.
Pick where you live, then scroll. First a target, then the years, the tax wrapper, the assets, the blend, the fees, and finally what the pot pays you, stress-tested against the worst retirements on record. Every chapter writes a line on your receipt. No ads, no accounts, nothing stored.
How much is actually enough?
Before any saving, a destination. A common rule of thumb, quoted by the Social Security Administration, is that you will need about 80% of your pre-retirement income to live comfortably. Set your income and the guide turns it into a pot size.
Target income = your income x the replacement rate. 80% is the common planning rule (SSA pub EN-05-10035): retirees usually need less than a full salary because saving, commuting and payroll tax stop. Big travel plans? Slide it up. Mortgage paid off? Down.
Defaults to the average retired-worker benefit ($24,974/yr, April 2026). Yours depends on your earnings record and claiming age, from roughly half to over double the average: check your statement at ssa.gov/myaccount.
The years do most of the lifting.
Compounding pays growth on last year's growth. That makes the years you start with worth more than almost any other choice in this guide, including how much you put in. Set what you can save each month; the next chapter will boost it.
Projected pot so far: $1,638,195
Where the money lives decides what it costs you.
The same dollar grows very differently depending on the account it sits in. Most 401(k) plans match part of what you put in, commonly 50 cents per dollar up to a slice of your salary. An IRA has no match but keeps the tax break; traditional defers the tax, Roth pays it up front. A plain taxable account is the baseline: no help, no rules.
2026 limits: $24,500 401(k) deferral · $7,500 IRA. Saving across more than one account? Model each in the full Retirement calculator; the guide tracks one wrapper to stay readable.
What each asset class actually does.
Every portfolio is built from a few raw ingredients. Stocks own a slice of businesses. Bonds lend money and collect interest. Cash parks savings at short-term rates. Bitcoin is a scarce digital asset with a short but dramatic history. Adjust the inputs below to explore what your money would have become in each class.
Returns are each index's own-currency series; we apply the percentages to your contributions and ignore exchange-rate moves. Stocks line uses the S&P 500 because it is the longest verified series; other equity indexes appear in chapter 5's picker. Starting year moves the window; each class is normalised to your amount at its own first available year.
$100 invested in 1928 grew to $1.16m by 2025
Worst year: -43.8% (1931)
Rises with corporate earnings and economic growth; falls sharply in recessions and financial crises.
$100 invested in 1928 grew to $8k by 2025
Worst year: -17.8% (2022)
Rises when interest rates fall or investors seek safety; falls when rates rise or inflation spikes.
$100 invested in 1928 grew to $3k by 2025
Never lost a nominal year (worst: 0% in 2014)
Tracks short-term rates; barely moves in nominal terms but loses ground to inflation over decades.
$100 invested in 2011 (from 2011) grew to $29m by 2025
Worst year: -73.6% (2018)
Chapter 7’s stress test replays bitcoin as stocks, which flatters it; treat any bitcoin share as the most fragile part of a plan.
Highly volatile; driven by adoption cycles, regulatory news, and speculative sentiment.
How you mix the assets sets the speed.
No real portfolio holds a single asset class. Named funds package cash, bonds, and equities into one product for one annual fee. The preset cards below are widely available index funds; pick one and the guide uses its exact composition. If none fits, open the customise panel to mix your own. The standalone calculator is uncapped on bitcoin; the guide caps it at 10% to keep the blends sensible.
Examples, not recommendations.
Cash 0%, Bonds 40%, Stocks 60%, Bitcoin 0%
S&P 500: USD total return, data 1928+
Example products, not recommendations. Fees and compositions verified 2026-06-12 from provider pages; see chapter 6 for what fees do.
The quiet leaks never take a year off.
A 1% fee sounds like nothing. But it is charged on the whole pot, every year, forever, and it also eats the growth that money would have earned. Inflation does the same to what the final number can actually buy.
The pot is not the finish line.
Your pot has to pay you for decades. How long it lasts depends on what the market does the year you retire, how you invest it, and how much you take out. The 4% rule is a starting point, not a guarantee.
How past retirees fared
Cohorts replayed on the longest verified record (US S&P 500 / Treasuries / CPI, 1928–2025) with your class weights, survival shown up to 40 years.
The 25x rule held in most historical cohorts, but it broke in the worst start years, typically when a sharp market fall hit right at retirement. What helped: spending a little less in a bad year, working one or two extra years to let the pot recover, or converting part of the pot into a guaranteed income. Flexibility in the first decade of drawdown is worth more than any rule of thumb.
Your whole plan, on one slip.
Everything you set above, and the pot it builds. In today’s money that pot is worth $657,026. The link carries the numbers, and your data never touches a server.
Both in today’s buying power: the nominal pot at 67 is $1,638,195, deflated at 2.5% inflation.
Or keep the date and treat the surplus as a buffer for bad market years (see chapter 7)
Fees are already out of the pot; inflation drag is lost buying power, not a further subtraction. Pot and income are at-retirement money.
Go deeper on any step
Each chapter above has a full calculator behind it, with more options and a proper write-up of how the numbers work.
Retirement Calculator
Project your pot at retirement with contributions, growth, fees, inflation and an employer match.
Index Fund Calculator
Backtest any blend of cash, bonds, stock indexes and bitcoin through verified historical returns.
S&P 500 Historical Return Calculator
Backtest a lump sum through real S&P 500, T-bill and T-bond returns from 1928 to 2025.
Safe Withdrawal Calculator
Turn a pot into income with the 4% rule and see how long the money lasts.
Inflation Calculator
See what inflation did to buying power across decades in the US, UK and Eurozone.
How this guide works
Every chapter shares one plan. First you set a target pot, then each step (the years you give it, the tax wrapper it sits in, the blend of cash, bonds, stock indexes and bitcoin, and the fees and inflation drag) recomputes the same projection and writes a line on the running receipt, ending with what the pot pays you each year in retirement. Nothing is stored and no account is needed; the link you copy at the end carries your numbers in the URL.
How big does my retirement pot need to be?
A widely used shortcut is 25 times the yearly income your savings must provide, the inverse of the 4% withdrawal rule. In the UK, the Retirement Living Standards (Pensions UK, updated June 2026) price a minimum, moderate and comfortable retirement in pounds per year for singles and couples. In the US a common rule of thumb, quoted by the Social Security Administration, is to replace about 80% of pre-retirement income. Subtract what the State Pension or Social Security covers, and 25x the remainder is your target pot.
How much should I save for retirement?
A common rule of thumb is 10% to 15% of gross income, including any employer contribution, starting as early as you can. The honest answer from the first chapter is that the start date matters more than the amount: a modest monthly sum started at 25 routinely beats a much larger one started at 40, because the early money compounds for longer.
What return should I assume on my investments?
Over 1928 to 2025, US large-company stocks returned roughly 10% a year with dividends reinvested, 10-year government bonds roughly 4.6%, and cash-like Treasury bills roughly 3.3% (all before inflation; data from NYU Stern). The guide blends the stock and bond figures for your chosen mix. Lower assumptions are safer for planning, and a diversified portfolio can behave differently from the US market alone.
Do investment fees really matter?
More than almost anything else you can directly control. Fees are charged on the whole pot every year, so they compound against you: over a 35-year save, the difference between a 0.2% index fund and a 1.5% managed fund is routinely a five-figure sum, sometimes six. The fees chapter shows the exact cost at your numbers.
What is an employer match worth?
In the US, a typical 401(k) match adds 50 cents per dollar you contribute up to a slice of salary, an instant 50% return before any growth. In the UK, auto-enrolment requires a total of at least 8% of qualifying earnings into your workplace pension, of which your employer pays at least 3%, and basic-rate tax relief tops up your own contributions. The wrapper chapter shows what that boost compounds into by retirement day.
Is the 4% rule safe?
Mostly, historically. The drawdown chapter replays your blend through the worst retirement start years on record (1929, 1973, 2000 and 2008) with inflation-linked withdrawals, using the longest verified US return series. In most historical sequences a 4% starting withdrawal survived 40 years; in the worst ones it did not, and the fixes were flexibility on spending, retiring slightly later, or converting part of the pot to a guaranteed income. UK savers can also compare a level and an RPI-linked annuity at dated best-buy rates.
Figures are estimates for guidance only. Historical returns are nominal own-currency figures (Aswath Damodaran, NYU Stern, 1928 to 2025; MSCI 1998+; FTSE Russell 1986+; JST Macrohistory gilts) and do not predict future performance. Retirement Living Standards are Pensions UK figures dated June 2026; annuity rates are a dated best-buy snapshot; contribution limits and allowances cited are for the 2026 US tax year and 2025/26 UK tax year. Funds and ETFs shown are examples, not recommendations. This is not financial advice; consider speaking to a qualified adviser.