Free tools for subcontractors

Free tools that work out what you are owed and when. Each one shows its working, so you can check it and use it in your own letters.

Updated: 26 September 2026. By Jack Butler-Kettle, Construction Claims Consultant.

Calculators

Work out the statutory interest at 8% over base rate and the £40, £70 or £100 fixed sum on a late payment, with the working shown.

Work out the due date, the Payment Notice and Pay Less Notice deadlines and the final date for payment, with bank holidays counted.

Compare the Hudson, Emden and Eichleay formulas for head office overheads after a delay, side by side, with the working shown.

See the referral deadline, the decision date and the extensions in a construction adjudication, counted from the notice.