Project the growth of your investments over time. Enter a lump sum, monthly contributions, return rate and investment period to see your portfolio value and inflation-adjusted real return.
Last updated: April 2026
Investment details
Historical UK stock market average: ~7% nominal, ~4.5% real. Past performance is not a guide to future results.
Investment projection
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How investment returns compound over time
The investment return calculator uses monthly compound growth - your contributions and the existing balance both grow at the stated annual rate, applied as a monthly rate (annual rate ÷ 12). Over long periods, the compounding effect becomes substantial. At 7% annual return, money doubles roughly every 10 years. £10,000 invested for 30 years becomes approximately £76,000 without any additional contributions - the original £10,000 has generated £66,000 in growth.
The importance of the tax wrapper
Investment returns are affected significantly by how they are sheltered from tax. Inside a Stocks and Shares ISA, all gains, dividends and income are free from capital gains tax and income tax. Outside an ISA (in a General Investment Account), gains above the annual CGT allowance (£3,000 in 2026/27) are taxed at 18% (basic rate) or 24% (higher rate), and dividends above the £500 annual allowance are taxed at 10.75% or 35.75%. Over a 20-year investment period, the tax drag on a GIA can meaningfully reduce total returns. Using your annual ISA allowance (£20,000) before investing in a GIA is almost always the right approach.
Real versus nominal returns
The nominal return is what appears in your portfolio. The real return accounts for inflation - what that money can actually buy. At 7% nominal return and 2.5% inflation, the real return is approximately 4.4% (calculated as (1.07/1.025) - 1). This calculator shows both figures so you can see the inflation-adjusted purchasing power of your future portfolio, not just the headline number.
Frequently asked questions
The UK stock market (FTSE All-Share) has delivered average nominal returns of approximately 7–8% per year over the long term, with significant year-to-year variation. Global diversified indices (MSCI World) have delivered similar or slightly higher returns. These are before charges - a low-cost index fund with a 0.2% annual charge delivers a net return of around 6.8%. Higher-cost funds can significantly erode returns over time. Past performance does not guarantee future results, but long-term history suggests equity markets deliver meaningfully positive real returns over periods of 10+ years for patient investors.
Pound-cost averaging means investing a fixed amount at regular intervals (monthly, for example) rather than investing a lump sum all at once. When prices fall, your fixed contribution buys more units; when prices rise, it buys fewer. Over time, this smooths out the average cost per unit relative to lump-sum timing. For most regular investors contributing monthly from salary, pound-cost averaging is the natural approach and removes the psychological burden of trying to time the market.
For most people, the answer is pension first, then ISA. Pension contributions benefit from tax relief at your marginal rate (20% for basic rate, 40% for higher rate taxpayers), which is an immediate return on investment. Employer matching further amplifies this. ISAs offer no upfront tax relief but complete flexibility - you can access the money at any time without restriction, unlike a pension which is locked until age 57. A common approach is to maximise employer pension matching (free money), then use ISAs for additional savings, then return to the pension for further tax-efficient retirement saving.