ISA Growth Projection
Project how your ISA balance could grow with regular contributions.
What is the ISA Growth Projection?
An ISA growth projection calculator estimates how an Individual Savings Account balance could grow over time, combining a starting balance with regular monthly contributions and compounding at an assumed annual growth rate. It works month by month: each month the existing balance grows by the monthly-equivalent rate, then that month's contribution is added, and the cycle repeats for the number of years you're projecting — the gap between the final balance and the amount you actually paid in is the projected growth. To sense-check the output, remember growth compounds on both your original balance and every contribution you've already made, so returns accelerate the longer money stays invested; also check your total annual contributions stay within the current ISA allowance published on gov.uk.
How it works
This projection compounds your starting balance and regular monthly contributions at an assumed annual growth rate, month by month, over your chosen time horizon — the same compounding principle behind our compound interest calculator, applied specifically to an ISA savings/investment context.
UK context
An ISA (Individual Savings Account) is a tax-efficient wrapper — growth and income within an ISA are generally free of Income Tax and Capital Gains Tax, up to an annual contribution allowance set by the government each tax year. There are several ISA types (Cash, Stocks & Shares, Lifetime, Innovative Finance), each with different rules and risk profiles, but the tax-free growth principle and shared annual allowance apply across the standard types.
Tips
- Check the current annual ISA allowance on gov.uk before assuming you can contribute the full amount used in a projection — exceeding it in a given tax year isn't permitted.
- A Stocks & Shares ISA's growth rate is never guaranteed and can go down as well as up — treat any assumed growth rate in a projection as illustrative, not a promise.
- Contributing regularly (rather than a single lump sum) can smooth out the effect of market timing on a Stocks & Shares ISA, though it doesn't guarantee better returns.
Frequently asked questions
Is ISA growth really tax-free?
Yes, generally — growth and income within an ISA are free from Income Tax and Capital Gains Tax, within the annual contribution allowance set by the government. Withdrawals are also normally tax-free.
How much can I pay into an ISA each year?
There's an annual ISA allowance set by the government each tax year, which can be split across different ISA types (subject to specific rules) — always check the current allowance on gov.uk, since exceeding it isn't permitted.
Is a projected growth rate guaranteed?
No — any growth rate used in a projection is an assumption for illustration purposes only. Cash ISA rates can change, and Stocks & Shares ISA values can go down as well as up; past performance doesn't guarantee future returns.
A quick note
This is an illustrative compounding projection using the growth rate you enter — it isn't a guarantee or a promise of actual returns. Investment values can fall as well as rise.