Best Investment & Savings Calculators in the UK
Plan your UK investments with compound interest, ROI, and retirement savings calculators.
CalculatorZone Editorial Team11 min readPublished Updated
The value of investments can fall as well as rise, and you may get back less than you put in. This article is general information, not personal advice.
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, 2026/27), completely sheltered from Income Tax and Capital Gains Tax: Open the ISA Calculator
- Compound Interest Calculator — Shows the power of compounding over time; essential for understanding why starting early matters more than the amount: Open the Compound Interest Calculator
- Investment Returns Calculator — Projects portfolio growth at different assumed annual return rates (4%, 6%, 8%, 10%): Open the Investment Returns Calculator
- Dividend Yield Calculator — Calculate gross and net yield on dividend-paying stocks after Dividend Allowance (£500 in 2026/27) and dividend tax rates: Open the Dividend Yield Calculator
- Capital Gains Tax Calculator — Estimate CGT on shares, funds, or property disposals. Basic rate: 18%; Higher rate: 24% (the same for shares, funds and property). Annual exemption: £3,000 in 2026/27: Open the Capital Gains Tax Calculator
ISA vs Taxable Account: Tax Saved Over 10 Years (£20,000/yr invested, 7% growth)
This example assumes the whole portfolio is sold in a single tax year, uses the £3,000 annual exempt amount, applies the 18% or 24% Capital Gains Tax rate to the whole taxable gain, and ignores dividend tax, fees and how the gain interacts with your other income.
| Scenario | Portfolio Value (10yr) | Tax Drag | Value After Tax |
|---|---|---|---|
| ISA (tax-free) | £289,700 | £0 | £289,700 |
| Taxable (Basic Rate) | £289,700 | ~£15,600 CGT | £274,100 |
| Taxable (Higher Rate) | £289,700 | ~£20,800 CGT | £268,900 |
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 are a popular choice because lower fees leave more of the return with you. 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.