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Compound Interest Calculator

Project how your savings could grow with compound interest. Adjust for ongoing contributions, fees, and inflation, then compare with an optional second scenario to visualise different strategies side-by-side.

How the calculation works

  • Management fees reduce the annual return before compounding, so you see the rate you actually receive.
  • Inflation shows the future value in today’s money, giving you both nominal and real balances.
  • Scenario B is pre-populated to demonstrate a comparison — tweak or clear the fields if you only need one scenario.
Investment scenarios

Scenario A

Primary plan

Pre-filled with a primary approach. You can update the values or clear the investment length to hide Scenario B.

£

Recurring contribution added at the start of every month.

£

One-time deposit applied before compounding begins.

Expected average annualised return before fees.

Scenario B

Comparative Plan

Pre-filled with a contrasting approach. Update the values or clear the investment length to hide Scenario B.

£

Use this scenario to test an alternative monthly savings plan.

£

One-time deposit applied before compounding begins.

Expected average annualised return before fees.

Tip: to remove Scenario B, leave the investment length empty or set it to 0.

Scenario A highlights

Nominal vs real
Nominal final value
£90,917.86
Real final value
£74,584.31
Total invested
£70,000.00
Total interest (nominal)
£20,917.86

Scenario B highlights

Comparison
Nominal final value
£173,826.39
Real final value
£118,367.31
Total invested
£137,600.00
Total interest (nominal)
£36,226.39

Growth over time

Tracks the cumulative balance at the end of each year. Hover over the chart to compare balances between scenarios.

Keep in mind

Returns seldom arrive evenly, and this calculator assumes consistent monthly contributions and smooth compounding. Use the results as a planning guide only and consult a qualified advisor for personalised investment advice.

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