ISA Calculator for Cash and Stocks and Shares

Welcome to our ISA Calculator. If you're considering opening an Individual Savings Account (ISA) or

Updated: June 10, 2024
Mark Tovey

Written By

Mark Tovey

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ISA Calculator for Cash and Stocks and Shares

Welcome to our ISA Calculator. If you're considering opening an Individual Savings Account (ISA) or already have one and are planning how to utilise your annual allowance, this tool is for you.

Whether you're looking for security or aiming for growth, understanding these options will help you make an informed decision.

Let's start by exploring what an ISA is and the different types available.

What is an ISA?

An ISA, or Individual Savings Account, is a tax-efficient savings and investment account available to residents in the UK.

The primary advantage of an ISA is that it allows you to earn interest on savings or gains from investments without paying tax on the earnings.

This includes income from interest, dividends, and capital gains, making ISAs a popular choice for individuals looking to maximise their financial assets.

Each tax year, you have an ISA allowance (£20,000 in the tax year 2024/25) which sets the limit on how much money you can contribute across different types of ISAs.

This makes ISAs an essential tool for both saving and investing, catering to a variety of financial goals and risk appetites.

ISA Calculator

ISA Calculator

Future Value: £0

Different Types of ISAs

ISAs come in various forms, each designed to suit different financial goals and saving needs. Here’s a brief overview of the main types:

  • Cash ISAs - These are similar to standard savings accounts except that the interest earned is tax-free. They are ideal for savers who want a low-risk place to store their money.
  • Stocks and Shares ISAs - These ISAs allow you to invest in equities, bonds, and other securities. The returns could be higher than with Cash ISAs, but they come with greater risk as your capital can go up or down depending on market conditions.
  • Innovative Finance ISAs - These are for investments in peer-to-peer lending platforms. Returns can be higher than traditional savings accounts, but so is the risk, as these investments are not covered by the Financial Services Compensation Scheme (FSCS).
  • Lifetime ISAs - Specifically for young adults aged 18 to 39, these ISAs are intended to help save for a first home or retirement. You can save up to £4,000 each year until you are 50, with the government adding a 25% bonus to your savings, up to a maximum of £1,000 per year.

Cash ISA vs Stocks & Shares ISA

When deciding between a Cash ISA and a Stocks & Shares ISA, it’s important to consider your financial goals and risk tolerance.

Cash ISA:

  • Safety: Cash ISAs offer a safe place to keep your money with minimal risk of losing the principal amount invested.
  • Returns: Typically, returns are lower compared to Stocks & Shares ISAs due to lower interest rates.
  • Accessibility: Money in a Cash ISA is usually easier to access without facing market risks, making it suitable for short-term savings goals.

Also Read: Best Cash ISAs

Stocks & Shares ISA:

  • Potential for higher returns: Over the long term, Stocks & Shares ISAs can offer higher returns due to investments in the stock market, though this comes with higher volatility and risk.
  • Risk: The value of investments can go down as well as up, so there is a possibility of losing money, unlike in a Cash ISA.
  • Long-term investment: Best suited for long-term financial goals like retirement savings, where there is ample time to ride out market fluctuations.

Also Read: Best Stocks & Shares ISAs

What is the Purpose of the ISA Calculator?

Our ISA Calculator is designed to demystify the process of saving and investing, helping you learn how to effectively grow your funds within a tax-efficient environment.

Compounding is a powerful concept in finance where the returns on your investments generate their own returns. Essentially, it means that interest is calculated not only on your initial capital but also on the accumulated interest from previous periods. This effect can significantly increase the growth of your investments over time, especially within an ISA where these gains are not taxed.

ISAs serve as a "tax wrapper," which means that any money placed within them benefits from tax-free growth. You won't pay taxes on the interest, dividends, or capital gains from investments held within your ISA. This advantage can make a considerable difference in the amount you accumulate over the years compared to regular taxable accounts.

By using our ISA Calculator, you can visualise the potential outcomes of different saving strategies and investment choices. It allows you to experiment with various scenarios by adjusting your monthly contributions, investment period, and expected interest rates to see how these factors influence the growth of your savings.

This tool is incredibly useful for setting realistic financial goals. It helps you understand how long it might take to reach your objectives, whether you're saving for retirement, a child's education, or a significant purchase.

Ultimately, our goal is to empower you with knowledge and tools to make informed financial decisions. By understanding the principles of compounding and the benefits of ISAs, you can plan your financial future with confidence and clarity. So why not start exploring different ways to enhance your financial stability today?

Other Useful Tools at CompareBanks

Alongside our ISA Calculator, CompareBanks offers a couple of other practical tools that can help streamline your financial planning:

Mortgage Calculator: Perfect for those exploring home ownership or investment properties, this calculator allows you to input purchase prices, deposit amounts, mortgage terms, and interest rates to see potential monthly repayments. Whether you're buying your first home or considering a buy-to-let mortgage, this tool makes it easier to understand your financial commitments.

Interest-Only Buy-To-Let Mortgage Calculator: Specifically designed for property investors, this calculator focuses on buy-to-let properties where payments cover only the interest. It helps you estimate monthly interest payments and evaluate the profitability of rental investments.

These tools are designed to complement each other, providing a holistic approach to your financial planning needs. Whether you're saving, investing, or managing property finances, CompareBanks is here to help.


By using our calculator, you can play with different figures to understand how variations in monthly contributions, interest rates, and investment durations can affect the growth of your savings.

This insight is crucial for setting realistic financial goals, whether you're planning for retirement, saving for a child's education, or gathering funds for a significant purchase.

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