ISA Calculator
Use our ISA calculator to see what your ISA could be worth in the future.
Try our free ISA calculator
Our free ISA calculator offers a fast, straightforward way to compare how different cash ISAs compare with each other and ISAs offered by other providers.
The calculator lets you see how much interest you might earn depending on how much you deposit, the interest rate you are offered and how long you save for.
This can help you when deciding how to best use your tax-free ISA allowance, which for the 2024/25 tax year is £20,000 (or £4,128 for a Junior ISA).
Enter a lump sum, regular payment or both. Then just choose the length of your investment in years and the growth rate you’re aiming for.
Find out how much your ISA could be worth
Choose a growth rate
Cash ISA Calculator: Estimate Your Tax-Free Savings Growth
A Cash ISA is a simple, tax-efficient way to grow your savings. With the ability to earn interest without paying tax, Cash ISAs remain one of the most popular choices for savers.
Whether you’re planning for a big purchase or building an emergency fund, understanding how much your savings could grow is key to effective financial planning.
Our Cash ISA calculator is designed to help you estimate your potential savings growth by taking into consideration factors such as your initial deposit, monthly contributions, interest rate, and the length of time you plan to save.
This tool provides you with an estimate of how much your Cash ISA could be worth at the end of your savings term.
Mobile App only account. *Up to three withdrawals can be made within each 12-month period from the date of opening without affecting the interest rate. More than three withdrawals made within each 12-month period, a lower rate of 0.75% (variable) will be applied. The Moneybox Cash ISA includes a 4.70% AER variable underlying rate and a bonus rate of 0.47% for the first 12 months. Up to three withdrawals can be made within each 12-month period from the date of opening without affecting the interest rate. Transfer in any ISAs you hold with other providers into a Moneybox Cash ISA, entirely in-app. Covered by FSCS. If more than three withdrawals made within each 12-month period, a lower rate of 0.75% (variable) will be applied for the rest of that 12-month period. The lower interest rate of 0.75% will also apply if the account balance dips below £500, automatically returning to the higher interest rate when the balance returns to £500 or more again. Must be UK resident and be aged 18 or older
Mobile App only account. *Up to three withdrawals can be made within each 12-month without affecting the interest rate. More than three withdrawals made within each 12-month period, a lower rate of 3.00% (variable) will be applied. Includes a bonus of 0.88% AER (variable) if account held for 12 months. Transfer in any ISAs you hold with other providers. Interest rates drop if more than three withdrawals per year. Covered by FSCS. Rate when you transfer in your existing ISA – 4.04% AER (variable). Rate for each 12-month period after your first 12 months – 4.04% AER (variable). Rate when balance drops below £100 or after your fourth annual withdrawal – 3.00% AER (variable). Must be UK resident and be aged 18 or older
- Term: Instant Access
- Invest From: £1
Unlimited deposits and withdrawals. Interest paid annually. ISA transfers also allowed in. Maximum deposit £250,000. FSCS Protected. Winner of Platinum Feefo Trusted Service Award in 2024. Must be UK resident and be aged 18 or older
- Term: Instant Access
- Invest From: £100
Interest paid annually. Unlimited deposits and withdrawals. ISA transfers also allowed in (some providers charge a transfer fee). Open and manage online. FSCS Protected.. Must be UK resident and be aged 18 or older. After 12 months the interest rate changes to 1.45% AER variable. Online ISA is provided by OneFamily, savings in Post Office Cash ISAs are deposited with Bank of Ireland UK
How the Cash ISA Calculator Works
The Cash ISA calculator allows you to input key details about your savings plan to project your future balance.
Here’s how it works:
- Initial deposit: This is the lump sum you deposit when you open your Cash ISA. It can range from a small amount, such as £100, to the maximum annual allowance of £20,000.
- Monthly contributions: If you plan to regularly contribute to your Cash ISA, enter the amount you intend to save each month. Regular deposits can significantly increase the final value of your savings, thanks to the power of compound interest.
- Interest rate: Input the interest rate offered by your Cash ISA provider. The calculator will use this rate to estimate how your savings will grow. For fixed-rate ISAs, the interest rate is locked in for the term, while for variable-rate ISAs, it can change over time.
- Investment term: Choose how long you plan to keep your money in the ISA. The longer the term, the more time your savings have to grow, especially with compound interest.
After entering these details, the calculator will estimate your total savings at the end of the term, showing both the amount you’ve contributed and the interest earned.
Why Use the Cash ISA Calculator?
The Cash ISA calculator helps you visualise your investment growth over time, allowing you to plan more effectively for the future.
Here’s how it benefits you:
- Set realistic savings goals: Whether you’re saving for a home deposit or a rainy-day fund, the calculator lets you see how much your ISA could be worth based on your current savings habits.
- Maximise your allowance: With an annual limit of £20,000 (ISA rules), the calculator can help you optimise your contributions to make the most of your tax-free savings each year.
- Compare interest rates: You can adjust the interest rate input to see how different providers or ISA products could impact your final savings. This is useful when comparing fixed-rate vs. variable-rate ISAs.
How to Use the Cash ISA Calculator: Step-by-Step
Using the calculator is simple and straightforward. Here’s a step-by-step guide:
Step 1: Enter your initial deposit
Begin by inputting the amount you plan to deposit initially into your Cash ISA. This is your starting balance.
Step 2: Set your monthly contributions
If you intend to save regularly, enter your monthly contributions. Consistent saving helps grow your balance faster, especially when combined with compound interest.
Step 3: Input the interest rate
Enter the interest rate offered by your Cash ISA provider. If you’re using a fixed-rate ISA, this will be the rate you lock in for the term.
Step 4: Choose the term length
Decide how long you want to save. The longer you leave your money in the ISA, the more interest it will earn.
Step 5: View your results
The calculator will estimate your total savings at the end of the term, showing both the contributions you’ve made and the interest earned. This will give you a clear view of your potential savings growth.
Cash ISA vs. Other ISAs
While this calculator focuses on Cash ISAs, it’s worth noting that there are other types of ISAs, such as Stocks and Shares ISAs and Lifetime ISAs.
These options can offer different levels of growth depending on market conditions and government bonuses, but they also come with varying risks and conditions.
If you’re considering these other options, you’ll need a more specialised calculator designed for those products.
For example:
- Stocks and Shares ISA: Investments in this ISA type can grow at a higher rate but come with market risk.
- Lifetime ISA: Offers a 25% government bonus but is only available for specific purposes, like purchasing a first home or saving for retirement.
However, if you’re focused on secure, predictable savings, a Cash ISA is an excellent choice. Our calculator is tailored to help you make the most of your Cash ISA, projecting tax-free growth with guaranteed or variable interest.
Important Considerations When Using a Cash ISA Calculator
- Projections are not guaranteed: Calculators estimate potential returns based on assumptions, but actual growth may vary.
- Assumption of regular contributions: Many calculators assume consistent deposits, but your contribution pattern might differ, affecting results.
- Market fluctuations: Interest rates and economic conditions can change, influencing the returns on your Cash ISA.
- Potential changes to tax rules: Current tax benefits may change, affecting your future returns.
- Withdrawals affect interest: Most calculators assume no withdrawals; withdrawing funds can reduce your overall interest earned.
- Comparing interest rates: The calculator helps you compare rates, but small differences in rates can have a significant long-term impact on future investments.
- Planning contributions: It helps in determining how much you need to contribute regularly to meet your savings goals.
Maximise Your Savings with a Cash ISA
A Cash ISA is a reliable way to grow your savings without worrying about taxes on your interest.
By using our Cash ISA calculator, you can plan ahead, set achievable savings goals, and make the most of your annual allowance.
Whether you’re just starting your savings journey or looking for a secure place to grow your nest egg, the Cash ISA calculator gives you the insight you need to stay on track.
Explore your options, enter your details, and see how much your tax-free savings could grow over time.
Frequently Asked Questions
Can I use the Cash ISA calculator for Stocks and Shares ISAs?
No, this calculator is specifically designed for Cash ISAs. If you’re looking for projections on a Stocks and Shares ISA, you’ll need a stocks and shares ISA calculator that accounts for market growth and investment risk.
How accurate are the results?
The calculator provides estimates based on the information you enter. For fixed-rate ISAs, the projections are fairly accurate. However, for variable-rate ISAs, the actual interest earned may vary over time depending on changes to the interest rate.
What if I exceed the annual ISA allowance?
The annual ISA allowance for 2024/25 is £20,000. The calculator will not project contributions beyond this limit, and exceeding the allowance can result in penalties.