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Cash ISA Calculator

How much could your cash isa be worth?

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Cash ISA Calculator

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A cash Individual Savings Calculator is a program, mostly online, that helps you determine how much interest you could gain as interest on an ISA investment. While these tools only give a projection of the amount, they give valuable insight as to whether a certain interest rate is favorable and how much should be invested into the ISA regularly to give the best interest gains. A cash ISA calculator should not be used as the final determinant or decision maker when it comes to committing to a cash ISA. This is because it operates on assumptions to calculate a possible outcome on investment. That investment may gain more or less than estimated and is not an accurate measure.

Investment ISA Idea

Assumptions made on calculation

One of the assumptions made is that the individual will deposit money into the account on a regular basis. Cash ISAs give a lot of leeway when it comes to withdrawals and deposits. For that reason, it is not always necessary that an individual deposit money into the account on a regular basis in as long as the final tally on deposits does not exceed the cash ISA allowance limit.

Another assumption is that the market will be steady and the rates will be productive. Capital markets fluctuate all the time throughout the tax year. The market may grow or stunt considerably affecting the economical rates on conversion for the currency. Due to such changes therefore, the interest gained tends to fluctuate.

Another assumption made is that there shall be fixed tax rules throughout the duration of the tax year. The current tax allowance for ISAs exempts them from having to be taxed on interest made. However, the rules might change and in such a scenario, the tax rate could affect the projected figures.

It is also an assumption that there shall be no withdrawals made on the account. Most of the calculators work under the premise of compound interest. A withdrawal, which in reality will happen at one point or the other, has significant impact on interest.

Benefits of a cash ISA calculator

One of the benefits of using a cash ISA calculator is that it helps you predict your annual growth on a certain interest rate. From this prediction, you can then determine whether the interest rate offered is sufficient for your goals or whether you need to find a different rate elsewhere.

An ISA calculator also helps in determining how much money you should deposit on a regular basis, and at what time interval, to make it to the allowance limit, without having to compromise your financial situation.

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I found the way the different options are presented very clear - much more useful than some other comparison sites. I sent it to my daughter as well.


Very informative, find myself a good ISA account with best return in terms of interest.


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Excellent website - clear and helpful information about different products - and a trustworthy partner.


Easy to use website and up to date. Saved the link on my tablet.


Really simple to use and all the information was clear with lots of products available. The interest calculator was really handy too. Have bookmarked and will definitely use again.

Hannah Gordon

This was a really user-friendly site, and was very helpful when it came to comparing accounts and choosing my 2016 ISA.


Easy to use website and up to date. Saved the link on my tablet.


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Good advice and professional approach


Very helpful for getting my annual ISA

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Clear, concise and very professional outfit with an excellent choice of market leading deals.

Paul Tissington not only helped narrow down my choices for a Junior ISA but also provided additional practical information that helped demystify the whole process.

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Great selection of Isa products, useful information and a very user friendly site