Stocks & Shares ISA Calculator UK 2025

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By Mustafa Bilgic • Updated 20 February 2026 • 10 min read

Use our Stocks and Shares ISA calculator to project how your investments could grow, completely free from UK tax. Enter your annual investment, expected annual growth rate, and the number of years to see your projected portfolio value and the tax you save compared to a general investment account.

Risk warning: Investments can fall as well as rise. The value of your ISA can go down as well as up and you may get back less than you invest. Past performance is not a reliable indicator of future results. This calculator provides illustrative projections, not financial advice.

Stocks & Shares ISA Growth Calculator

Your Stocks & Shares ISA Projection

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What Is a Stocks and Shares ISA?

A Stocks and Shares ISA is a tax-free investment wrapper. Any investments held inside it are sheltered from UK tax - you pay no Capital Gains Tax (CGT) on profits, no Income Tax on dividends, and no tax on interest. You can invest up to £20,000 per tax year across all your ISAs combined.

Inside a Stocks and Shares ISA, you can invest in a wide range of assets: shares, investment funds, ETFs, investment trusts, bonds, and more. The choice of platform and investments is yours. Most long-term investors choose low-cost global index funds as their core holding.

ISA Allowance 2025-26

The annual ISA allowance is £20,000 per person per tax year. This has been unchanged since 2017-18. The allowance runs from 6 April to 5 April. Key rules:

Historical Stock Market Returns

Conservative (5%)

£10k/yr

20 years = £347k
Cautious assumption

Moderate (7%)

£10k/yr

20 years = £437k
FTSE 100 + dividends

Optimistic (10%)

£10k/yr

20 years = £630k
Global tech-heavy index

The FTSE 100 total return (including dividends reinvested) has averaged approximately 7-8% per year over the long term. The MSCI World index, which includes global developed market equities, has averaged closer to 8-10% per year. Remember these are pre-charge averages and include significant periods of decline.

Tax Benefits in Detail

The tax advantages of a Stocks and Shares ISA are substantial, particularly over long time periods:

The £1 million ISA: Could you build a £1 million ISA? Investing the full £20,000 allowance annually at 7% over 23 years would generate a portfolio worth over £1 million. Many ISA millionaires have achieved this. The key ingredients are: maximise your allowance, invest in diversified low-cost funds, and stay invested through market fluctuations.

Best Stocks and Shares ISA Platforms UK 2025

PlatformAnnual FeeFund Charge RangeBest For
Vanguard0.15% (max £375)0.06% - 0.22%Low-cost index funds
Trading 2120% (free)Fund dependentZero platform fee
Hargreaves Lansdown0.25 - 0.45%0.06% - 1.5%Wide investment choice
AJ Bell0.25% (max £3.50/mo shares)VariesShares and funds
InvestEngine0% (free)ETF charges onlyETF-only portfolios
Nutmeg0.25 - 0.75%Fund charges extraManaged portfolios

Investment Options Within a Stocks and Shares ISA

The range of investments available inside a Stocks and Shares ISA is broad:

Stocks and Shares ISA vs Pension

Both ISAs and pensions offer tax advantages for long-term investing, but they work differently:

For most people, contributing to a workplace pension (especially with employer matching) should come first. Once this is maximised, a Stocks and Shares ISA is an excellent second choice for flexible tax-free investing.

Lifetime ISA for First Home or Retirement

The Lifetime ISA (LISA) is a special ISA type for those aged 18-39. You can save up to £4,000 per year and receive a 25% government bonus (up to £1,000/year). The money can only be used to buy a first home (up to £450,000) or from age 60 onwards. Withdrawals for other purposes incur a 25% penalty (which effectively claws back the bonus plus some of your own money). See our Lifetime ISA calculator for projections.

Frequently Asked Questions

What is the Stocks and Shares ISA allowance for 2025-26?

The annual ISA allowance is £20,000 per tax year (2025-26). This can be split between different ISA types - Cash ISA, Stocks and Shares ISA, Innovative Finance ISA, and Lifetime ISA (limited to £4,000) - in any combination, as long as the total does not exceed £20,000.

What are the tax benefits of a Stocks and Shares ISA?

Inside a Stocks and Shares ISA, all growth, dividends, and interest are completely free from UK tax. There is no Capital Gains Tax (CGT) on profits, no Income Tax on dividends or interest, and no tax reporting required. This is a significant advantage over a general investment account where CGT rates are 18-24% on gains above the annual allowance.

What can I invest in within a Stocks and Shares ISA?

A Stocks and Shares ISA can hold individual UK and international shares, investment funds (unit trusts, OEICs), exchange-traded funds (ETFs), investment trusts, bonds, and gilts. The exact range depends on your platform. Most investors use index funds or ETFs as their core holding.

What is the average return from a Stocks and Shares ISA?

Historical returns depend on what you invest in. The FTSE 100 has returned around 7-8% annually including dividends over the long term. Global index funds tracking the MSCI World or FTSE All-World have returned 8-10% annually. Past performance does not guarantee future returns. Our calculator uses 7% as a conservative default.

How much does it cost to open and run a Stocks and Shares ISA?

Platform charges typically range from 0.15% to 0.45% per year of your portfolio value. Fund charges (ongoing charges figure) range from 0.07% for index funds to 0.75%+ for actively managed funds. For a £10,000 portfolio, annual costs might be £15-50 for the platform plus £7-75 for fund charges. Low-cost index funds on a low-cost platform minimise drag on returns.

Can I withdraw from a Stocks and Shares ISA?

Yes, with most flexible ISAs you can withdraw money at any time and re-deposit it in the same tax year without affecting your annual allowance. However, you should consider investment timing risk - if markets have fallen, withdrawing means crystallising a loss. A Stocks and Shares ISA is best viewed as a long-term (5+ year) investment.

Stocks and Shares ISA vs Cash ISA: which is better?

For time horizons of 5 years or more, Stocks and Shares ISAs have historically outperformed Cash ISAs significantly. Over 20 years, the stock market has consistently beaten savings rates. However, investments can fall as well as rise, whereas cash is stable. For short-term goals (under 3-5 years), Cash ISA is safer. For long-term wealth building, Stocks and Shares ISA typically wins.

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