Hometech
Carpet is bought by the running metre off a fixed-width roll. Which way it runs across the room can change the order by a metre or more.
— m
Running metres off the roll, whichever direction needs fewer
The room is a rectangle measured wall to wall; alcoves, bays and doorways need adding by hand. Every strip runs the full length of the room in the direction chosen, with the trimming allowance at both walls, and the strips side by side cover the other way with the allowance at both walls too. With a pattern, every cut is rounded up to whole repeats and each extra strip needs up to one more repeat so the pattern lines up at the seam. Pile direction should run the same way in every strip and ideally away from the main window or towards the door; the tool counts both ways and leaves that choice to you. **A fitter's measure on site is the order; this is the estimate before it.**
Broadloom Carpet for a Room: Strips, Seams, Pattern Match, Length to Buy & Waste — free, with the formula and a worked example, at Textile School.