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ISA Calculator 2021 – Calculate Your Projected Savings Here

Wondering whether it's worth putting your money into an ISA? Use our ISA calculator to see how much your savings might be worth if you started saving today.
Author: Kane Pepi

Last Updated: March 17, 2021

Please note that we are not authorized to provide any investment advice. The information on this page should be construed for information purposes only. We may earn commissions from the products mentioned on this site.

ISA Calculator
ISA Calculator

In the 20/21 UK tax year (April 5 2020 – April 5 2021), you can invest up to £20,000 in your personal ISA. You can either invest the whole £20,000 into a single ISA, or alternatively, spread it across a range of different ISAs. For example, you could put £15,000 into a stocks and shares ISA, and the remainder into an Innovative Finance ISA.

With that being said, trying to calculate how much money you are likely to make from your ISA is no easy feat. To help you along the way, we’ve created the ultimate ISA calculator for the 2020/21 tax year.


Table of Contents

Contents [show]


    Try out our ISA Calculator Now:

    Your Initial Deposit

    Enter "0" for initial savings if there is no initial deposit.

    Initial Savings:
    Lenght of Investment:
    Begin Investment:
    Annual Interest Rate (APR %):


    Select "never" on frequency if no recurring transactions are made.

    Transaction Frequency:
    Deposit Each Cycle:
    Withdrawal Each Cycle:

    Income Taxes & Inflation

    Enter "0" in fields if you do not wish to adjust results.

    Annual Inflation (%):

    Here Are Your Results

    Total Amount Deposited:
    Total Amount Withdrawn:
    Interest Earned:
    Spending Power of Your Savings:
    Annual Percentage Yield (APY %):

    What to consider when using the ISA calculator?

    Although the ISA calculator can give you an idea as to how much your ISA savings will be worth in the future, it should only be used as a rough estimate. Here are some of the things that you need to consider when assessing the results.

    Lump Sum

    The best way to give your ISA savings a boost is to invest a lump sum. This will ensure that you are able to increase your savings in the fastest time possible. Don’t forget, you can’t inject more than £20,000 in a single tax year.

    Regular Savings

    In order to build your ISA accounts over time, it is important to inject cash regularly. Some people aside a couple of hundred pounds at the end of each month via direct debit, while others choose to do it whenever they have a bit of spare cash. Either way, try to estimate how much you are likely to invest long-term.

    Annual Growth Rate

    Perhaps the most challenging aspect to the ISA calculator is estimating your expected yield. If you are investing an ISA and in assets that offer fixed-rate interest payments such as savings bonds or peer-to-peer lending, then this is a lot easier. However, if you are looking to concentrate exclusively on your stocks and shares ISA, this is more challenging. The main reason for this is that it is virtually impossible to assess how much your chosen investments will make every year. Your best bet is to utilize an average based on your chosen risk levels.

    Time Scale

    You will need to try and estimate how long you intend on keeping your ISA investments. There are no restrictions with it comes to cashing out, meaning that you can withdraw your funds at any time. However, the ISA calculator can be a good motivator once you can see how much your cahs will grow over time. Hopefully, this prevents you from cashing out early.

    What are the limitations of the ISA calculator?

    The main limitation of the ISA calculator is that nobody can predict the future. The results that you get are based on your own personal projections. For example, if you decide to cash out your ISA before the time scale you entered into the calculator, then, of course, the results will differ greatly.

    Moreover, it is challenging to predict what annual growth non-fixed-rate investments will yield. Even in the case of certain fixed-rate investments, the outcome can be different to what you project. For example, while peer-to-peer lending offers a fixed-rate annual income, if the borrower was the default, this would affect the results of the calculator.

    All trading carries risk. Views expressed are those of the writers only. Past performance is no guarantee of future results. The opinions expressed in this Site do not constitute investment advice and independent financial advice should be sought where appropriate. This website is free for you to use but we may receive commission from the companies we feature on this site.

    Kane holds academic qualifications in the finance and financial investigation fields. With a passion for all-things finance, he currently writes for a number of online publications.

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