Use this Junior ISA calculator to estimate how a child's tax-free savings could grow by
age 18 and whether your planned contributions fit within the annual Junior ISA allowance.
Estimated value at 18
£0
Based on your planned contributions and growth rate to age 18
Within Junior ISA allowance
Total contributions
£0
Interest / growth earned
£0
Years to grow
0
Annual allowance used
£0
Junior ISA balance over time
Yearly breakdown
Year
Age
Contributions
Interest / growth
Closing balance
Assumptions
Estimates assume a fixed interest or growth rate until age 18 and use the current £9,000 Junior ISA allowance.
This version does not include fees, inflation, provider changes, Child Trust Fund transfers, or investment risk modelling.
How a Junior ISA works
A Junior ISA is a tax-free savings or investment account for children. In this calculator,
the projection runs to age 18, because that is when money is normally accessible by the
child.
The model is built for planning: starting amount, regular contributions, growth rate, and a
clear split between contributions and growth by the end of the timeline.
Junior Cash ISA vs Junior Stocks and Shares ISA
In a Junior Cash ISA, returns come from savings interest. In a Junior Stocks and Shares ISA,
returns come from investment growth, which can be higher over time but can also fall as well
as rise.
This version uses the same monthly projection engine for both and changes the explanatory
wording so results stay practical and easy to compare.
Junior ISA allowance explained
The Junior ISA allowance for the 2026/27 tax year is £9,000 per child. The allowance is not
per parent or per contributor, so all payments into that child's Junior ISA count towards
the same annual limit.
If planned annual contributions go above £9,000, this calculator still shows the projection
but flags the excess clearly as a warning for planning purposes.
When the child can access the money
A Junior ISA is designed for under-18s. Money is normally accessible by the child from age
18, so this calculator projects directly to that point.
If the child is already 18 or older, the calculator shows an invalid state because a Junior
ISA projection is no longer the relevant wrapper.
Who can pay into a Junior ISA
Parents, grandparents, friends, and other family members can usually pay into a child's
Junior ISA, but the annual allowance remains per child. Interest and investment gains within
the wrapper are tax free under current rules.
Frequently Asked Questions
For the 2026/27 tax year, the Junior ISA allowance is £9,000 per child.
Yes. Anyone can usually contribute, but the annual allowance is still per child rather
than per contributor.
Money in a Junior ISA is normally accessible by the child from age 18.
Yes. Interest and investment gains within a Junior ISA are tax free under current wrapper
rules.
A child can hold both types, but total contributions across Junior ISAs must stay within
the single annual Junior ISA allowance.
More UK Financial Calculators
Saving for yourself too? Try our Cash ISA calculator. Planning a future target? See our
savings goal calculator. Want to compare simple growth assumptions? Use our interest
calculator. Saving for your own first home as well? Our Lifetime ISA calculator is a useful
companion.