Investment Growth Calculator UK

Project a portfolio over any horizon with a starting lump sum, monthly contributions, your return assumption and the platform/fund fee drag. The calculator shows total growth, contributions, and the effect of fees compounded over your horizon.

Pennywise Finance Editorial

Standard future-value with monthly compounding. Fees applied as a continuous drag on monthly return. Projections are modelling only — real returns vary year to year.

Fact-checked
Reviewed September 2026
About our calculators

Runs entirely in your browser — your numbers are never sent to a server.

Your numbers

Starting lump sum£

Monthly contribution£

Expected annual return%

Global equity long-run 6-8%. Balanced 60/40 4-6%.

Combined annual fee (platform + fund)%

DIY ETF 0.2-0.5%. Managed 0.75-1.5%.

Years

Result

Final value—

Total contributed—

Growth—

Fees paid (compounded impact)—

What return should I use?

Based on long-run historical global equity returns:

Global equity index (100% stocks): 6-8% nominal (real returns ~4-6% after inflation)
Balanced 60/40 portfolio: 4-6%
Bond-heavy (30/70): 3-4%

These are long-run averages. Real markets have strongly negative years. For planning, use the lower end for conservatism.

Why fees matter so much

A 0.5% fee drag compounds. Over 30 years at 7% gross, a 0.5% fee reduces the final pot by around 14%. A 1.5% fee cuts it by ~35%. Fund choice and platform choice compound into life-changing differences.

What this calculator does NOT model

Market volatility (returns are not smooth)
Inflation (figure is nominal, not real)
Taxes outside wrappers (use ISA Growth or Pension Pot calculator)
Sequence-of-returns risk (critical near retirement)

Frequently asked questions

Is 7% a realistic UK return?

7% nominal is a reasonable long-run global equity assumption. Over any specific 10-year period actual returns can range from strongly negative to double digits.

Should I subtract inflation?

For planning you want REAL returns (after inflation). Subtract ~2-3% from the nominal rate for a conservative real projection.

Does fee really cost that much?

Yes. Compare total fee impact at this calculator vs the Investment Fee Calculator. 1% a year compounded over decades is substantial.

Projections assume a fixed annual return — real markets do not return the same figure every year. Capital at risk. Past performance does not guarantee future results. General information only, not personalised financial advice.