IT IS MY YEAR.My year
Menu

SMALL CONTRIBUTIONS. A LONGER VIEW.

What could your monthly habit become?

Explore the effect of time, regular contributions and compounding. Change the assumptions to see how much the outcome can vary.

YOUR WHAT-IF

Start with a monthly amount.

The starting figures are hypothetical examples, not recommended contributions, returns or provider charges. Change them to explore different outcomes. Your entries are not saved.

ILLUSTRATED VALUE AFTER 20 YEARS

£41,951

At 5% annual return before 0.25% annual percentage costs.

Money you put in£25,000
Illustrated growth after costs£16,951
Value in today’s money£28,232At 2% annual inflation

An illustration, not a forecast. Investments can fall in value and you could get back less than you put in.

At year 20, contributions total £25,000 and the illustrated pot is £41,951. The expandable table below contains values for every year.010.5k21k31.5k42kYear 0Year 10Year 20
Illustrated valueMoney paid inValues in pounds, before inflation

CHANGE THE ASSUMPTION, CHANGE THE OUTCOME

See more than one possible path.

The same £100 a month for 20 years, using different constant annual returns. All include your 0.25% percentage costs. These examples have no assigned probability and are not the best or worst possible outcomes.

What does compounding do?

When returns stay invested, future returns can apply to both your contributions and earlier growth. With these assumptions, your £1,000 starting amount plus £100 each month adds up to £25,000 paid in. The illustrated pot is £41,951 after 20 years.

For cash savings, this can mean earning interest on earlier interest. For investments, it means compounding total returns, with any dividends reinvested. Returns vary, losses also compound, and growth is never guaranteed.

How the calculator works

We convert your effective annual return into a monthly rate and add contributions at each month’s end. Percentage costs are modelled as an annual reduction, spread monthly. The monthly multiplier is ((1 + return ÷ 100) × (1 − costs ÷ 100)) raised to the power 1/12. Each month: new balance = previous balance × multiplier + monthly contribution.

Contributions and assumed rates stay constant. Returns are reinvested. We do not model tax, fixed fees, dealing charges, currency conversion charges, withdrawals or changes to ISA rules. Add applicable recurring percentage costs yourself. Today’s-money figures divide the final pot by (1 + inflation ÷ 100) for each elapsed year; nominal contributions are not adjusted for inflation.

Real market returns do not follow smooth lines. This tool does not show volatility, the timing of losses, or the full range of possible outcomes. Displayed amounts are rounded; calculations use unrounded values. General education, not personal financial advice.

UNDERSTAND THE ACCOUNT AS WELL AS THE INVESTMENT

What is a Stocks & Shares ISA?

A home for your investments.

A Stocks & Shares ISA is a UK tax wrapper that can hold eligible investments such as shares and funds. Under current rules, investment income and capital gains within it are generally free of UK Income Tax and Capital Gains Tax. An ISA does not create a return or protect you from market losses.

Read MoneyHelper’s ISA guide

Your allowance is shared.

For the 2026/27 tax year, the total ISA contribution allowance is £20,000 across your ISAs. A Stocks & Shares ISA is generally available to UK residents aged 18 or over. The tax year runs from 6 April to 5 April. Rules and tax treatment can change.

Check the current GOV.UK rules

Match the money to the goal.

Investing is for money you can leave invested for a number of years and afford to see fall in value. Keep access needs, emergency savings and commitments in mind. Holding investments for longer does not guarantee a gain.

Explore independent investing guidance

Compare the whole cost.

Look at platform charges, fund costs, dealing fees and currency conversion as well as the headline commission rate. A spread of investments can reduce reliance on one company, but cannot remove investment risk. Review the provider’s account type and terms before opening anything.

Keep learning with finance books

UK information checked 4 October 2026. The calculator is a general illustration: it does not assume that all contributions fit within an ISA, calculate your remaining allowance or predict future tax rules. If moving an existing ISA, use the provider’s ISA transfer process and check the current rules.

ORDINARY LINKS · NO AFFILIATE COMMISSION

Investment platforms to explore.

Examples for your own research.
No provider is matched to your calculator result.

STOCKS & SHARES ISA

Trading 212

Explore its Stocks ISA for shares and exchange-traded funds (ETFs). Check currency conversion, applicable fund costs and the terms for the account you choose.

Read Trading 212 Stocks ISA details

STOCKS & SHARES ISA

Freetrade

Explore its Stocks and Shares ISA and available investments. Compare plan options, currency conversion charges and investment costs.

Explore Freetrade ISA

STOCKS & SHARES ISA

InvestEngine

Explore its ETF-focused Stocks and Shares ISA. Compare available portfolio services and their charges, including the underlying ETF costs.

Explore InvestEngine ISA

Capital at risk. These links are not personal recommendations. Investments can fall as well as rise, and you may get back less than you invest. Check current charges, eligibility and terms on each provider’s website. The illustrated returns above are not rates offered by these providers.