Best Investment & Savings Calculators in the UK
Plan your UK investments with compound interest, ROI, and retirement savings calculators.
Introduction
The UK offers world-class tax-sheltered investment wrappers — the Stocks and Shares ISA and the Lifetime ISA among them — alongside a Capital Gains Tax annual exemption and dividend allowance. Used correctly, these tools dramatically accelerate wealth building. These calculators help you model your investment journey with UK-specific rules built in.
Key Calculators
- ISA Calculator — Models growth inside a Stocks and Shares ISA (£20,000 annual allowance, 2025/26), completely sheltered from Income Tax and Capital Gains Tax: Try it →
- Compound Interest Calculator — Shows the power of compounding over time; essential for understanding why starting early matters more than the amount: Try it →
- Investment Returns Calculator — Projects portfolio growth at different assumed annual return rates (4%, 6%, 8%, 10%): Try it →
- Dividend Yield Calculator — Calculate gross and net yield on dividend-paying stocks after Dividend Allowance (£500 in 2025) and dividend tax rates: Try it →
- Capital Gains Tax Calculator — Estimate CGT on shares, funds, or property disposals. Basic rate: 10% (18% property); Higher rate: 20% (24% property). Annual exemption: £3,000 in 2025: Try it →
ISA vs Taxable Account: Tax Saved Over 10 Years (£20,000/yr invested, 7% growth)
| Scenario | Portfolio Value (10yr) | Tax Drag | Net Gain |
|---|---|---|---|
| ISA (tax-free) | £289,700 | £0 | £289,700 |
| Taxable (Basic Rate) | £289,700 | ~£17,900 CGT | £271,800 |
| Taxable (Higher Rate) | £289,700 | ~£35,700 CGT | £254,000 |
Tips for UK Investors
Max your ISA allowance before investing in taxable accounts — the tax shelter is permanent once funds are inside. If you haven't used last year's ISA allowance, you cannot carry it forward, so act before 5 April each year. For long-term investing, low-cost index funds tracking the FTSE All-World or S&P 500 have historically outperformed most actively managed funds after fees. Consider a SIPP (pension) alongside your ISA for even greater tax relief, especially if you're a higher-rate taxpayer receiving 40% relief on contributions.