United Kingdom Compound Interest Calculator
This calculator estimates compound interest growth on GBP savings and investments in the United Kingdom. Calculations apply user-defined rate, term, and contribution inputs, with reference rates published by the Bank of England, HMRC, and FSCS.
Enter Investment Details
Input the GBP value you want to convert to its inflation-adjusted equivalent.
Select Compounding Frequency
Choose how often interest compounds — Weekly, monthly, quarterly, or annually.
Review the Projection
Each tab shows the breakdown — Summary, Composition, Compare scenarios, and Milestones.
UK Compound Interest Calculator
Project investment growth — figures shown in GBP
Summary
Investment Summary
An initial investment of £10,000 with £500 contributed monthly at 6.0% annual interest (compounded monthly) grows to £91,940 over 10 years.
Total contributions add up to £70,000, with £21,940 earned in interest — including £2,180 of compound growth (interest earned on previously earned interest).
Growth Projection
Yearly Breakdown
Year-by-year contributions, interest and balance. Figures reflect the view setting (Future £ or Today's £).
| Year | Contributions | Interest | Total Invested | Balance |
|---|
Scenario Comparison
How different choices affect the final balance, all using your selected period and rate.
Compounding Frequency Comparison
Same principal, contribution, rate and period — only the compounding frequency changes.
| Frequency | Final Value | Difference vs Annual |
|---|
Investment Milestones
Estimated time to reach common UK savings and investment milestones, based on the inputs above.
When you'll reach common targets
| Target | Years | Estimated Year |
|---|
UK Investment Options
Common investment types available to UK savers and investors, with typical historical returns and risk levels. Tap any option for detailed considerations.
High-Interest Savings Accounts
Very Low RiskFSCS-protected savings with competitive interest rates. Government guaranteed up to £120,000 per person, per authorised institution (raised from £85,000 on 1 December 2025). Easy access or notice accounts available.
Advantages
- FSCS protected (£120K)
- Easy access options
- No market risk
- Personal Savings Allowance
Considerations
- Lower returns vs shares
- Rates can change
- Tax on interest above PSA
- Inflation risk
Fixed-Rate Savings Bonds
Very Low RiskFixed-rate savings locked in for a set term (1–5 years). FSCS protected. Guaranteed rate for the term regardless of Bank of England changes.
Advantages
- FSCS protected
- Locked-in rate
- Predictable returns
- Various term options
Considerations
- Funds locked away
- No early access
- Miss future rate rises
- Tax on interest
UK Gilts & Corporate Bonds
Low–Medium RiskUK Government gilts, NS&I products and corporate bonds. NS&I is 100% government backed. Suitable for income-focused investors.
Advantages
- Regular income stream
- Lower volatility
- NS&I 100% backed
- Portfolio diversification
Considerations
- Interest rate risk
- Credit / default risk
- Lower growth potential
- Complex for beginners
Cash ISA
Low–Medium RiskTax-free Individual Savings Account for cash savings. £20,000 annual ISA allowance (2025/26). All interest is 100% tax-free with no income tax or CGT.
Advantages
- 100% tax-free interest
- FSCS protected
- Flexible withdrawals
- Transfer between providers
Considerations
- £20K annual limit
- Rates may be lower than non-ISA
- Allowance use-it-or-lose-it
- Cash ISA cap dropping to £12K from 2027/28 (under-65s)
Gold & Precious Metals
Medium RiskPhysical gold from The Royal Mint, gold ETFs on the LSE, or gold funds. UK gold sovereigns are CGT-free. Traditional inflation hedge and safe-haven asset.
Advantages
- Inflation hedge
- Safe-haven asset
- Sovereigns CGT-free
- Portfolio diversification
Considerations
- No income / dividends
- Storage costs (physical)
- Price volatility
- Currency risk (USD priced)
Workplace Pension (Default)
Medium RiskAuto-enrolled workplace pension with balanced default fund. Minimum 8% total contribution (5% employee, 3% employer). Tax relief at the marginal rate applies.
Advantages
- Employer contributions
- Tax relief on contributions
- 25% tax-free lump sum
- Professional management
Considerations
- Locked until 55 (rising to 57)
- Limited fund choice
- 75% taxed as income
- Annual allowance £60K
Stocks & Shares ISA (ETFs)
Medium–High RiskTax-free ISA wrapper for ETFs tracking the FTSE 100, S&P 500 or global indices. £20,000 annual allowance. No CGT or dividend tax on gains within the ISA.
Advantages
- Tax-free gains & dividends
- Very low fund fees (0.05–0.5%)
- Instant diversification
- Flexible withdrawals
Considerations
- Market risk exposure
- £20K annual limit
- Platform fees apply
- Capital can fall
UK Property (Direct)
Medium–High RiskUK residential or commercial property. Combines rental income (4–6% yield) with capital growth. Buy-to-let is taxed on gross rent (Section 24 rules apply).
Advantages
- Tangible asset
- Rental income stream
- Leverage available
- Main residence CGT-free
Considerations
- Stamp duty (higher rate)
- Section 24 tax rules
- Illiquid investment
- Management costs
UK REITs
Medium–High RiskLSE-listed REITs such as Land Securities, British Land and Segro. Access commercial property without buying directly. Hold in an ISA for tax-free distributions.
Advantages
- Liquid (trade on LSE)
- Low entry cost
- Hold in ISA / SIPP
- Regular distributions
Considerations
- Share market volatility
- Interest rate sensitive
- REIT income taxed
- Management fees
SIPP (Growth)
Medium–High RiskSelf-Invested Personal Pension with growth-focused equity investments. Full control over investments. Tax relief up to 45% (additional rate taxpayers).
Advantages
- Tax relief 20–45%
- Full investment control
- 25% tax-free at 55
- IHT efficient
Considerations
- Locked until 55 (rising)
- Higher short-term volatility
- £60K annual allowance
- Platform fees apply
Stock Market (FTSE Direct)
High RiskDirect share investment on the LSE with potential for capital growth and dividends. Hold in an ISA for tax-free gains. CGT annual exempt amount: £3,000 (2025/26).
Advantages
- Growth potential
- Dividend income
- Hold in ISA / SIPP
- Ownership in companies
Considerations
- High volatility
- Capital can be lost
- Requires research
- CGT outside ISA
Cryptocurrency
Very High RiskDigital assets such as Bitcoin and Ethereum via FCA-registered exchanges. HMRC treats crypto as a CGT asset — the £3,000 CGT annual exempt amount applies.
Advantages
- High growth potential
- 24/7 global market
- Portfolio diversification
- CGT allowance applies
Considerations
- Extreme volatility
- Can lose 50%+ quickly
- Not allowed in ISA / SIPP
- Security & scam risks
Frequently Asked Questions
Common questions about compound interest, ISAs, pensions and tax in the UK. Answers reference HMRC, FCA, Bank of England and FSCS official guidance.
Important Disclaimer
For educational and informational purposes only. This calculator produces estimates based on the inputs provided and assumes a constant compounding rate over the projection period. Tax-free allowances referenced reflect the 2025/26 tax year: ISA allowance GBP 20,000 (Cash ISA scheduled to reduce to GBP 12,000 for under-65s from 6 April 2027 per Autumn Budget 2025), Junior ISA allowance GBP 9,000, pension annual allowance GBP 60,000, Money Purchase Annual Allowance GBP 10,000, Personal Savings Allowance GBP 1,000 (basic-rate) / GBP 500 (higher-rate) / GBP 0 (additional-rate), starting rate for savings GBP 5,000, and Capital Gains Tax annual exempt amount GBP 3,000 with rates of 18% / 24% from October 2024. The Bank of England base rate referenced is 3.75%, and the Normal Minimum Pension Age is scheduled to rise from 55 to 57 from 6 April 2028. Past investment performance is not a reliable indicator of future returns.
No warranty of accuracy. While Money Snap takes reasonable care to source figures from official authorities (HMRC, FCA, Bank of England, FSCS, MoneyHelper), this calculator is provided "as is" without any express or implied warranty as to accuracy, completeness, timeliness, or fitness for any particular purpose. Allowances, tax rates, base rates, and pension rules change frequently — figures shown may be out of date following Budget announcements, Monetary Policy Committee decisions, or regulatory updates. Individual circumstances including tax residency, earned income level, scheme rules, and other allowances claimed may materially affect actual outcomes.
Not financial advice. Money Snap is not authorised or regulated by the Financial Conduct Authority (FCA) and does not hold permission to provide regulated financial advice in the United Kingdom. Information provided is general in nature only and does not take into account your personal circumstances, financial situation, or objectives. Results do not constitute financial, investment, tax, or pension advice and use of this calculator does not create an advisory relationship. Before acting on any figure shown, obtain personal advice from an FCA-authorised financial adviser (search the FCA Register), a Chartered Tax Adviser via the Chartered Institute of Taxation, or seek free guidance from MoneyHelper. Tax queries can be addressed directly to HMRC.
Limitation of liability. To the maximum extent permitted by law, Money Snap accepts no liability for any loss, damage, cost, or expense — direct or indirect — arising from reliance on this calculator or the information it produces. Investment products (stocks, ETFs, REITs, cryptocurrency, structured products) carry capital risk and may fall as well as rise in value; FSCS investment protection of up to GBP 85,000 per person, per FCA-regulated firm applies only where the firm fails (it does not cover investment losses from market movements). FSCS deposit protection of up to GBP 120,000 per person, per authorised institution (raised from GBP 85,000 on 1 December 2025) applies only to eligible cash deposits at banks, building societies and credit unions. Users are responsible for verifying all figures with the relevant authority before relying on them. Use of this calculator is subject to our Terms of Use.
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