Tools / Finance & Money / ISA Calculator

ISA Calculator

Enter your ISA savings and contributions to project the tax-free balance.

Current ISA balance (£)

Monthly contribution (£)

Annual growth / interest (%)

Years

ⓘEstimate for general information only — not financial, tax or legal advice. Always check the official figures (GOV.UK / HMRC) or speak to a qualified adviser before making decisions.

An ISA lets your savings or investments grow completely free of income tax and capital gains tax. This projects the future value of an ISA from your current balance, regular monthly contributions and an assumed growth rate. Remember the annual ISA allowance is £20,000 (2025/26) across all your ISAs, and investment returns are never guaranteed.

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Frequently asked questions

What is the ISA allowance?

For 2025/26 you can pay up to £20,000 into ISAs across the tax year. This can be split across cash, stocks and shares, and other ISA types.

Cash ISA or stocks and shares ISA?

Cash ISAs are lower risk with modest interest; stocks and shares ISAs can grow more over the long term but can fall in value. This tool projects either with your chosen rate.