A full fitted sheet is designed to fit a mattress 54 inches by 75 inches, while a queen-size mattress measures 60 inches by 80 inches. The queen mattress also may also be deeper than the full sheet corner pockets can accommodate. You can add fabric to the edges and corners to make the full fitted sheet fit a queen mattress. Choose a similar colour to camouflage the alteration, or select a contrasting colour or print to create bold, custom bedding. Opt for elastic-gathered corners to ensure a snug fit.
Lay the fitted sheet on a flat surface and cut the elastic and hem away from the edge of the sheet with scissors. Turn the corners of the sheet inside out and cut next to the seam line at each corner to remove the corner seams.
Iron the cut edges and the cut corners. Note that each corner of the sheet will now have a square-shaped cutout. Trim the cut edges and corner if needed to make them straight.
Measure both sides and both ends of the sheet along the cut edges. Cut across the width of your fabric using the longest measurement from your sheet. Set the remaining shorter piece aside. From the longer piece, cut two strips of fabric, each 8 inches wide and the length of the sheet's cut edge.
Align the edge of one of the long fabric strips with a long edge of the sheet, right sides together. Insert pins every 2 to 3 inches to hold the fabric in place. Use the sewing machine to stitch a 1/2-inch seam, removing the pins as you go. Repeat this process for the other three edges.
Lay the sheet wrong-side up on the ironing board and press the seam allowances to one side. Sew the length of each seam allowance through all three layers, stitching 3/8-inch away from the seam. This finishes and reinforces the seam.
Lay the sheet out flat and measure both sides of each corner from the edge of the newly added fabric to the point at the top of the corner cut. Add 1 inch both horizontally and vertically to these measurements. Using these measurements, cut a square for each corner from the shorter piece of fabric that you previously set aside.
Fold 1/2-inch of fabric to the backside along two adjoining sides of each square. Position a square in each corner of the sheet with the folded edges overlapping the cut corner edges by 1/2-inch. Insert pins into the fabric through all three layers to hold the pieces together.
Sew 1/8-inch away from the folded edges on each square, removing the pins as you go. Raise the sewing machine presser foot to pivot the fabric at each corner and continue sewing down the adjoining side. Sew another line of stitching on each square, 1/4-inch inside the first stitch line.
Draw a gentle arc with the pencil across each corner of the sheet to round it off. Draw the line freehand, or use a dinner plate or other round object as a template and trace around the curve. Trim each corner on the drawn line.
Fold over 1 inch of fabric to the backside around the perimeter of the sheet and press. Fold the raw edge in toward the crease and press. Sew around the perimeter of the sheet, 3/8-inch from the edge.
Cut four pieces of elastic, each 36 inches long. Match the middle of each elastic piece with the centre of a corner arc on the inside edge of the sheet. Insert a pin through the middle of the elastic to hold it in place.
Set the sewing machine to a zigzag stitch. Sew the elastic to the inside hem of the sheet, starting from the pin in the centre and going toward to one end, stretching the elastic taut as you sew. Remove the pin and sew the elastic in the opposite direction, from the centre to the end, again stretching the elastic taut as you sew. Repeat on each corner. You sheet is ready to be placed on the mattress.
Add a similar border to the sides and top of a full flat sheet to make a matching queen flat sheet.