Future Value Calculator

Updated August 2026 Last reviewed 10 August 2026 Savings & Investments

This calculator projects the future value of a lump sum. It answers the question "if I invest £X today, what will it be worth in N years?"

Enter your lump sum, expected annual return and the investment period.

Your details

Cash: 2-4%. Stocks & Shares ISA (long term): 5-7%

Results

Future value
£26,532.98
After 20 years
Growth earned
£16,532.98
Growth multiple
2.65×
Original lump sum
£10,000.00

How the lump sum grows

26,533
10,000
£10,000Year 10£26,533

How the calculation works

We believe numbers should be transparent. Here is the formula behind this calculator.

Future value = present value × (1 + rate ÷ periods)⁽ᵖᵉʳᶦᵒᵈˢ × ʸᵉᵃʳˢ⁾

Worked example

Worked example: £10,000 at 5% for 20 years

Future value = £10,000 × 1.05²⁰ ≈ £26,533.
Growth earned: about £16,533.
Compounding does the heavy lifting — 65% of the final figure is growth, not your original money.

Important assumptions

  • Assumes a constant annual return for the whole period.
  • Returns on investments vary and can be negative in some years.
  • No contributions are added — for regular saving use the savings or ISA calculator.

Frequently asked questions

What is future value?

It is what a sum of money today will be worth at a future date once growth is compounded on it. It lets you compare investments and plan long-term targets.

How do I know what return to use?

Cash savings currently pay around 3-5% AER. A diversified Stocks & Shares ISA has historically returned roughly 5-7% a year over long periods, but that is not guaranteed.

Should I add inflation?

If you want a real (after-inflation) figure, subtract your expected inflation rate from the return. Our inflation calculator shows how much of your growth is real.

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Related guides

New to the topic? Read a plain-English guide on savings & investments, with worked examples and tips.

These calculations are estimates for guidance only and are not professional financial, tax or legal advice. UK rates and rules change, so always verify important figures with official GOV.UK / HMRC information or speak to a qualified professional. See our full disclaimer.