To make arm covers for a sofa, measure the length of the arm at the back and seat cushions, the arm's width and its height, and use these measurements to cut a fabric into pieces of the required size. Sew the fabric pieces together appropriately using a seam and hem of 1/2 inch.
To determine the length of the arm of a sofa, measure it from one end till the back and seat cushions. When measuring at the seat cushion, take the measurement on the arm's outer side. Increase the measurements taken by 1 inch to account for the hems and seams.
To measure the arm's width, measure at the widest portion towards the arm's front side, and to measure its height, determine the distance between the arm's top and the seat cushion. If the arm of the sofa has a rounded front, trace this shape on a paper piece, increase its size by 1/2 to account for the seam, and use the tracing as a template to cut the fabric.
Using these measurements, cut two fabric pieces, one to cover the arm from the top and the other to cover its front end. On the rear side of the first fabric piece, stitch the hemline. Sew the second fabric piece to the first piece's front side. If required, attach the pieces together using pins, and then stitch them together. Finally, hem the bottom edge of the cover.
Repeat the entire process to stitch the second arm cover.