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ISA Savings Calculator

Estimate how your ISA savings could grow based on your starting balance, monthly contributions, interest rate and time period.

Your Details

Overview

Use this ISA Savings Calculator to estimate how much your ISA could be worth over time. Enter your starting balance, monthly contribution, expected annual interest rate and savings term to see your projected balance and growth.

How it works

The calculator adds your starting balance to the future value of your regular contributions, then applies the chosen growth rate over the selected term. For monthly compounding, it uses a monthly rate and monthly contribution schedule. For annual compounding, it uses an annual growth rate and an approximate yearly contribution approach. The result shows your estimated final balance, total contributions and total growth.

How to use this calculator

  1. 1Enter your initial ISA deposit.
  2. 2Add the amount you plan to contribute each month.
  3. 3Enter the expected annual interest or growth rate.
  4. 4Choose the number of years you want to save.
  5. 5Select the compounding frequency and review the estimated balance and growth.

Example Calculation

Initial deposit

$5,000

Monthly contribution

$300

Annual interest rate

5%

Savings term

10

Compounding frequency

monthly

Estimated ISA balance

N/A

With a £5,000 starting balance, £300 monthly contributions, 4.5% annual growth and a 10 year term, the projected ISA balance would be about £52,000, with total growth of roughly £11,000.

Frequently asked questions

What does this ISA Savings Calculator estimate?

It estimates the future value of your ISA based on your starting amount, regular monthly contributions, growth rate and savings term.

Does this calculator include the ISA allowance?

No. It does not check whether your planned contributions stay within the current annual ISA allowance.

Is the growth rate guaranteed?

No. The calculator assumes a fixed rate for illustration, but actual savings rates or investment returns can change over time.

What is the difference between monthly and annual compounding?

Monthly compounding adds growth more frequently, which can slightly increase the final balance compared with annual compounding at the same stated rate.

Can I use this for a cash ISA or a stocks and shares ISA?

Yes. For a cash ISA, use an expected savings interest rate. For a stocks and shares ISA, use an assumed average annual return, understanding that actual returns may vary.

Does the calculator include fees or charges?

No. It does not deduct platform fees, fund charges or account fees, so your actual result may be lower if charges apply.

Explore Related Calculators

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Assumptions and warnings

Assumptions

  • Results are estimates based on a constant annual rate over the full term.
  • Monthly contributions are assumed to be made consistently throughout the savings period.
  • The calculator does not account for changes in ISA rules, contribution limits or provider fees.
  • Taxes are not included because eligible ISA growth is generally tax sheltered under current UK rules.

Warnings

  • This calculator provides an estimate only and is not financial advice.
  • Investment returns and interest rates can change, so actual ISA growth may be higher or lower.