ISA calculator

Compare cash and stocks & shares ISAs. See how much your ISAs could be worth in 20 years.

If you invest


here's what you might have


Based on estimated
interest rates

Stocks & shares



Higher than expected

Lower than expected


Remember that with a stocks & shares ISA, as with all investing, your capital is at risk. View sources.

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Please bear in mind

ISA rules apply. This does not include effects of tax or inflation. Forecasts are not a reliable indicator of future performance. Projected returns are based on past data under conditions of normal variability and it cannot be assumed that such variability will remain the same in the future.

Cash ISA returns

Nutmeg calculations based on data from Bank of England, Bloomberg as at 20/2/15. Money market rates have been used to estimate future interest rates at monthly and yearly intervals up to 10 years ahead. ISA rates are calculated monthly based on the historic premium of ISA deposit rates (excluding unconditional bonuses) over a money market rate. Lower and higher bands are estimated as a rate 0.75% below and above the expected rate in year two and 1% thereafter. Rates beyond ten years are assumed to equal the ten year rate.

Stocks & shares ISA returns

The projections are based on estimated long-term average returns for a portfolio of equities and government bonds, in different percentages depending on the risk level, using historic volatility of each asset class since 1986. We have assumed a 1.0% annual management fee, which has been deducted from the projections shown. We also assume income is re-invested. For more information read our article on How we forecast potential investment returns.