Free tool, no sign-up needed
Start at 20 or start at 35: same money, wildly different ending
Compounding is the one piece of money maths where being early beats being clever. Pick a monthly amount you could actually manage and see what fifteen years' head start is worth by 65.
Assumed yearly growth
Retirement age fixed at 65. Growth compounds monthly and ignores fees and inflation.
Start at 20, total at 65
£202,644
you put in £54k over 45 years
Start at 35, total at 65
£83,226
you put in £36k over 30 years
The gap
£119,418
the cost of waiting 15 years, for only £18k more paid in
£100 a month, two different start dates
hover to compare any age
Illustration only, not financial advice. Growth rates are assumptions, not promises. Real investments go down as well as up, and past performance doesn’t predict the future.
What this means
Compounding means your growth earns growth. In year one that’s pennies, which is why it feels underwhelming: the curve only bends properly after a decade or two. That delay is exactly why starting at 20 beats starting at 35 so dramatically: the early money gets the longest run, so the 20-year-old’s extra contributions are small but the extra compounding on them is enormous.
The practical takeaway isn’t “invest hundreds a month as a student”. It’s that the habit matters more than the amount. £25 a month started at 20 can outrun £100 a month started at 35 on the same assumptions. Getting the account open and the direct debit running is most of the battle; you can raise the amount when your income does.
In the UK, the usual home for long-term money is a stocks & shares ISA: you can put in up to £20,000 a year and all growth and withdrawals are completely tax-free. A Lifetime ISA adds a 25% government bonus if the money is for a first home or retirement. Only invest money you won’t need for years (anything you might need this term belongs in savings, not the market), and remember investments can fall as well as rise.
Like tools that tell you the truth?
HeadStart members get the full versions with their real numbers, plus scholarships, mentoring and a plan that starts before freshers’ week.
Keep going