French cuffs are an elegant variation on the traditional button-down shirt. Not only does the French cuff's folded-back appearance lend more formality to the shirt, it also presents an opportunity for further embellishment with cufflinks. Cufflinks are the bit of jewellery used in lieu of buttons to hold the cuff together. French cuffs are not difficult to make, they simply require a bit of alteration to an existing pattern.
Follow your shirt pattern's instructions for mapping and cutting shirt cuffs, noting the following exceptions on the pattern: Double the width of the cuff and add additional seam width. When you have this number, add an additional 3/4 inch to allow for extra width when using large cuff links. For example, if the width of the cuff on your pattern is 2 inches, you should end up with a cuff 4 3/4 inches wide.
Cut the fabric using the pattern and exceptions as a guide.
Sew cuffs by seaming the cuff ends together and folding in half, right-side out. Pin the cuff to the right side of the sleeve, matching the seams. Serge the seam around the cuff with a serger, or use a narrow zigzag stitch with a regular sewing machine.
When finished, iron French cuffs in a fold-back arrangement.
Add a button and hole to the cuff if desired, or two buttonholes if cuff links will be used.
When in doubt of the length of the longer French cuff, go with the longer. Remember, it is easier to cut off extra, but it is impossible to add the fabric back on after it has been cut.