Hi Ray,
I do not do carpets, but let me say you this:
If you quoted your customer by square meter then just write it down:
Number of square meter such and such multiply by prise per square meter such and such = total prise is such and such.
If you gave a general quote for the job than I would advise you to make an invoice mentioning your “hourly charges” and materials if applicable.
Good luck,
Arthur
