Rates & sources
Compound growth assumes reinvested returns and no platform fees. Past performance is not a guide to future returns.
Source: FCA — Investment basics — figures refreshed at the start of each tax year.
When to use this calculator
- Before choosing between saving, investing, or increasing your monthly contribution.
- When you want to compare best-case, base-case, and cautious return assumptions.
- When you need a quick projection before making a longer-term portfolio decision.
A realistic US planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Initial Deposit ($)
$70,000
Monthly Contribution ($)
$70,000
Annual Interest Rate (%)
5%
Years
10 years
After entering these figures, compare final value, total deposited and interest before deciding which scenario looks strongest.
How to read your results
Final Value
Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.
Total Deposited
This is the headline outcome, but it is most useful when viewed alongside the supporting metrics below it.
Interest
Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.
Common mistakes
- !Assuming a constant return without checking a more conservative growth rate.
- !Forgetting to include ongoing contributions, fees, or tax wrappers where relevant.
- !Focusing only on the final balance instead of the path required to reach it.
What to do next
- Test a cautious, expected, and optimistic growth rate instead of relying on a single projection.
- Compare this result with related savings or retirement tools before committing more money.
- Use the linked guides to understand which assumptions matter most over longer periods.
Frequently asked
Use arrow keys to navigate items, Enter or Space to expand/collapse.
End-of-article next steps
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