Stocks & Shares ISA Calculator
Estimate your future tax-free investment growth, total contributions, and compound interest earned over your chosen time horizon.
Calculate Your ISA Growth
Enter your initial investment, monthly contributions, expected annual return, and time horizon to instantly see your estimated tax-free portfolio value.
Investment Estimator
Get a clear breakdown of your total contributions and compound growth.
How it Works
Understanding your ISA projections
Initial & Monthly Inputs
We combine your starting lump sum with your planned monthly contributions to establish your total capital invested over time.
Compound Growth
We apply your expected annual return rate, compounded monthly, to simulate how your investments grow on top of previous gains.
Tax-Free Advantage
Unlike a General Investment Account (GIA), the growth calculated here is free from Capital Gains Tax and Dividend Tax within the ISA wrapper.
Final Projection
The tool outputs your total estimated portfolio value, clearly separating your own contributions from the market-generated growth.
Typical Returns by Asset Class
A general overview of historical average annual returns for different investment portfolios (before inflation).
| Asset Class / Portfolio | Historic Avg. Annual Return | Risk Level |
|---|---|---|
| Global Equity Index | 7% – 10% | Medium to High |
| UK Equity (FTSE All-Share) | 6% – 9% | Medium to High |
| Balanced (60% Equity / 40% Bonds) | 5% – 7% | Medium |
| Corporate Bonds | 3% – 5% | Low to Medium |
| Cash / Money Market | 1% – 5% (Variable) | Very Low |
ISA Investment FAQ
Answers to the most frequently asked questions about Stocks and Shares ISAs, allowances, and tax rules in the UK.
A Stocks and Shares ISA is a tax-efficient investment account available to UK residents aged 18 and over. Any capital gains, dividends, or interest earned within the ISA are free from UK Capital Gains Tax and Income Tax, making it a highly efficient way to build long-term wealth.
For the 2024/2025 tax year, the overall ISA allowance is £20,000. You can invest all of this into a single Stocks and Shares ISA, or split it across different types of ISAs (such as a Cash ISA, Innovative Finance ISA, or Lifetime ISA) as long as the total contributions do not exceed £20,000.
Yes. Unlike a General Investment Account (GIA), you do not pay Capital Gains Tax on profits or Dividend Tax on income generated within a Stocks and Shares ISA. Furthermore, you do not need to declare ISA earnings on your Self Assessment tax return.
Yes. The value of your investments can go down as well as up, and you may get back less than you invested. The calculator provides estimates based on historical averages, but past performance is not a reliable indicator of future results. It is generally recommended to invest for at least 5 years to ride out market volatility.