ISA Calculator
Initial lump sum (£)
Monthly contributions (£)
Time horizon (years)
Expected annual return (%)
ISA allowance used this tax year (£)
£-
Final Value
£-
Total contributed
£-
Estimated growth
Estimated ISA value after X years
Estimated ISA value after X years
The dotted line shows what happens if you invested just £50 more per month.
Small changes can add up - explore scenarios in the Advanced Planner
ISA Plan provides educational calculators and planning tools. We do not provide financial advice.
How to use the ISA Calculator
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Enter your monthly contribution (and any lump sum)
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Choose an expected annual return and time horizon
- Compare scenarios by adjusting contributions or years
What people often do next
Review & adjust
Many users adjust their contributions, time horizon, or expected returns to see how small changes can affect long-term outcomes.
Consider how to invest or save
After modelling their ISA, some users look at investment platforms or savings providers that support regular contributions, low fees, and flexible access within an ISA.
Explore more advanced planning
Others can choose to explore more detailed planning. such as combining different ISA types or modelling multiple tax years.