Bow ties are typically worn for formal occasions when you want to look your best -- however, you can't look your best if your bow tie doesn't properly fit your neck. A bow tie shouldn't be wider than your neck or extend down past the tips of your shirt collar. If you have a fitted bow tie that no longer fits, you will need to have it tailored or replaced to fix the problem. However, a bow tie with an adjustable buckle or hook can be shortened or lengthened to your preference.
Slide the buckle or latch to the number that matches your neck measurements. If your bow tie doesn't have measurements, you will have to adjust it yourself.
Slide the buckle to the left or right to lengthen or shorten the bow. If you have a bow tie with a hook adjustment, slide the latch to adjust the length, then attach the hook before tying.
Tie the bow or fasten the clip if it's a pre-tied bow tie. Inspect the bow tie in the mirror to make sure that it's the proper length. Untie the bow and adjust if necessary.
Although adjustable bow ties allow you to change the length of your tie, they're not considered as respectable as fitted bow ties. An adjustable bow tie can be converted to a fitted bow tie by your tailor, who will custom fit it to your neck measurements.