Interest Calculator

New Square Chambers is pleased to make available the following calculator, which is freeware and can be used from this website without charge. Full instructions for using this Interest Calculator, and important legal notices, are further down this page.

• Instructions

  To use the calculator:

  Step 1 – Choose your starting date
  Select the starting date of your choice using the drop-down arrows next to each selection box. The day of the week will be calculated automatically for you. When you first open the Interest Calculator, the date is automatically set to today’s date. As the calculator takes today’s date from your system clock, it is important to make sure that your system date is correctly set for this function to work properly.

  Step 2 – Choose your ending date
  Select the ending date of your choice using the drop-down arrows next to each selection box. The day of the week will be calculated automatically for you. When you first open the Interest Calculator, the date is automatically set to today’s date. As the calculator takes today’s date from your system clock, it is important to make sure that your system date is correctly set for this function to work properly.

  Step 3 – Enter your principal sum
  Enter the principal sum on which you want interest to be calculated. You should not enter any currency sign. Nor should you enter any commas in the number.

  Step 4 – Enter your rate of interest
  Enter the annual rate of interest which you wish to apply to your principal sum. You should not enter any percentage sign. Nor should you enter any commas in the number.

  Step 5 – Calculate
  Press the button marked “Calculate” to carry out the calculation. On the right hand side of the form will be displayed the number of days difference between your starting date and your ending date, the interest on the principal sum (rounded to two decimal places), and the total of the principal sum plus the interest (again rounded to two decimal places).

  Method of calculation:

  The interest is calculated as simple interest using the conventional approach used by litigation lawyers in England and Wales. This approach is to calculate the annual amount of interest on the principal sum, then divide by 365 to obtain a daily amount of interest, and then multiply this daily amount by the actual number of days in the relevant period. Note that the calculation excludes the starting date itself (ie. day number 1 is the day after your starting date) but includes the ending date.

• Legal notices

  Disclaimer

  Every effort has been made to ensure that this calculator functions correctly, and members of Chambers themselves use it. However, no liability can be accepted for any errors which might arise in its operation, and use is entirely at the user’s risk.

  Copyright

  Copyright in this calculator vests in the Head of Chambers for the time being of New Square Chambers. However, this calculator is freeware and may be used on this website without charge for any commercial or non-commercial purpose.

  Feedback

  If you have any comments (whether good or bad) on this calculator or if you spot any errors, New Square Chambers would be only too pleased to hear about them. Please e-mail us. Thank you.

  © Copyright New Square Chambers 2026 | Head of Chambers at New Square Chambers | version 3.1