UK Savings & Investment Tool
Compound Interest Calculator
See exactly how your money grows — with ISA vs taxable comparison, year-by-year breakdown, and scenario planning built for UK savers.
Calculator
Yearly Breakdown
ISA vs Taxable
Compare Scenarios
💷 Your Savings Plan
Initial lump sum
£
Regular contribution
£
Annual interest rate
5.0%
Time period
20 yrs
Advanced options
Compounding frequency
Contribution timing
Annual step-up in contributions
0%
Inflation rate (for real value)
2.5%
Final balance after 20 years
£0
Total contributed
£0
Interest earned
£0
Growth multiple — your money grows 1.0× its contributed value in real (inflation-adjusted) terms is shown below.
Inflation-adjusted (real) value: £0 in today's money.
📊 Year-by-Year Breakdown
| Year | Contributions | Interest earned | Balance |
|---|
Figures are rounded to the nearest pound. Interest earned is cumulative growth for that year, added to the running balance.
🏛️ ISA vs Taxable Savings Account
Your Income Tax band
Uses 2026/27 Personal Savings Allowance rules: £1,000 tax-free interest for basic-rate, £500 for higher-rate, £0 for additional-rate taxpayers. ISA interest is always 100% tax-free with no limit, using your £20,000 annual ISA allowance. This is a simplified estimate — speak to a financial adviser for personal tax planning.
✓ INSIDE A CASH ISA
£0
Tax-free growth — every penny of interest stays invested.
✗ TAXABLE ACCOUNT
£0
After Income Tax on interest above your PSA each year.
Using a Cash ISA instead of a taxable account saves you an estimated £0 over the full term.
⚖️ Compare Two Scenarios
SCENARIO A
Monthly contribution
£
Interest rate5.0%
SCENARIO B
Monthly contribution
£
Interest rate6.0%
SCENARIO A — FINAL BALANCE
£0
SCENARIO B — FINAL BALANCE
£0
Both scenarios use the same initial lump sum, time period and compounding settings from the Calculator tab.
Free UK Compound Interest Calculator by toolsforuk.com · Estimates only, not financial advice · Based on 2026/27 UK tax rules
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