Example result based on the prefilled values.
Result
18,193.97
Continue your plan
Useful next calculations
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.
- When you are deciding how many more years of contributions are needed to reach a specific target balance.
- When you want to see whether starting earlier versus contributing more each month produces a bigger outcome.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Present Value (£)
10000
Annual Interest Rate (%)
5%
Years
10 years
Compounds Per Year
10 years
After entering these figures, focus on result first and then rerun the tool with a more cautious assumption to understand the realistic range of outcomes rather than relying on a single estimate.
How to read your results
Result
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator uses the standard future value formula, applying compound interest to either a one-off lump sum, regular contributions, or a combination of both. You can adjust the compounding frequency to match your investment product — annual compounding suits most stocks and shares investments and ISAs, while monthly suits savings accounts that compound interest monthly.
The calculator assumes a fixed rate of return throughout the period, which is a simplification. In practice, investment returns vary each year. For long-term equity investments, many UK planners use a 5–7% nominal annual growth assumption before charges. Always deduct your platform and fund charges from the return rate to model a net figure. This tool does not account for tax, inflation, or changes in contribution levels over time.
Common mistakes
- !Using an assumption that is not supported by a current local quote, bill, statement or official source.
- !Treating a generic estimate as a lender, provider, payroll or tax authority decision.
- !Mixing monthly and annual inputs without converting them consistently.
- !Forgetting location-specific taxes, fees, eligibility rules or payroll deductions where they apply.
- !Testing only one scenario instead of checking how a cautious assumption changes the result.
What to do next
- Run a second scenario with a cautious assumption so you can see the downside clearly.
- Compare the result with the related calculators below before making a decision.
- Check current local rules, eligibility and provider terms before applying or committing money.
- Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.
- Use the result to prepare better questions for a lender, provider, adviser or employer rather than treating it as a final answer.
Frequently asked
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