Sofa slipcovers can bring new life to an old sofa or love seat, but they can also make your furniture look drab and frumpy if they do not fit properly. You can sharpen the look of a slipcover and make it fit like a glove with a few simple modifications.
Fit the slipcover onto the sofa with straight pins. Fold the fabric together over the seams and pin it together without catching the sofa fabric below. Insert all the pins so they face the same direction. Where you add a pin on one corner, match another pin in the same position on the opposite corner, using measuring tape to make sure the pins are the same distance from the seam. Stand back and check that the slipcover looks even and fits well.
Lift the slipcover carefully off the sofa and turn it inside out. Working on one seam at a time, hold the fabric together, remove the pin, and replace it on the inside of the cover.
Sew a straight stitch along the lines made by the straight pins with a sewing machine. Remove the pins as you sew.
Replace the slipcover over the sofa to check your work. Take out any stitches where the slipcover is pulled too tightly and restitch closer to the seam. Add stitches where the fabric bulges out too much.
Straight-stitch or zigzag-stitch next to the first row of stitches to finish your seam. Trim the fabric about 1/2 inch away from the finishing stitch.
Replace the newly snug-fitting slipcover on your sofa.