Junior ISA Calculator
Estimate how a Junior ISA could grow based on an initial deposit, monthly contributions, annual return and saving term.
Overview
A Junior ISA Calculator helps you estimate how much a child’s savings and investments could be worth over time. Enter an initial deposit, monthly contribution, expected annual return, investment term and annual fees to see a projected final balance, total contributions and estimated growth.
How it works
The calculator adds the future value of your initial deposit to the future value of a series of monthly contributions. It converts your expected annual return and annual fees into a net monthly growth rate, then applies monthly compounding across the full saving period. The estimated growth is the projected final balance minus the total amount paid in.
How to use this calculator
- 1Enter the starting amount you want to deposit.
- 2Add the monthly contribution you expect to make.
- 3Enter the annual return you want to assume.
- 4Add the annual fee percentage for the account or investments.
- 5Choose how many years the money will stay invested.
- 6Review the projected balance, contributions and estimated growth.
Example Calculation
Initial deposit
$1,000
Monthly contribution
$100
Expected annual return
5%
Years to invest
18
Annual fees
1%
Estimated final balance
$35,431
With a £1,000 initial deposit, £100 monthly contributions, a 5% annual return and 0.5% annual fees over 18 years, the projected balance would be about £38,600, with roughly £22,600 contributed and around £16,000 from estimated growth.
Frequently asked questions
What does this Junior ISA Calculator estimate?
It estimates the potential future value of a Junior ISA based on your starting deposit, monthly contributions, expected return, fees and saving term.
Does the calculator include Junior ISA annual allowance rules?
No. It focuses on growth based on the values you enter, so you should check the current annual subscription limit separately.
Why do annual fees matter?
Fees reduce the net growth rate, which can lower the final balance over long time periods.
Are investment returns guaranteed?
No. The return you enter is only an assumption, and real investment performance can be higher or lower.
Can I use this for a cash Junior ISA?
Yes, but for a cash Junior ISA you would normally enter an expected savings rate rather than an investment return.
Why is the growth figure only an estimate?
Because actual returns, charges, contribution timing and account rules can change over time, so real results are unlikely to match a fixed-rate projection exactly.
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Assumptions and warnings
Assumptions
- Results are estimates based on a constant annual return and constant annual fees over the full term.
- Contributions are assumed to be made monthly and growth is compounded monthly.
- This calculation does not model changes in market performance, contribution limits or charges outside the annual fee entered.
- The calculator assumes money stays invested for the full period entered.
- Tax treatment and Junior ISA rules may change over time.
Warnings
- This calculator provides an estimate only and is not financial advice.
- Investment returns are not guaranteed and the value of investments can go down as well as up.
- Check current Junior ISA contribution limits and account rules before making decisions.