Half of 3 5/8 inches is 1 13/16 inches (1.8125″, 46.04 mm).
How to Calculate It
Convert 3 5/8 to an improper fraction, divide by 2, then simplify. 3 5/8 = 29/8, divided by 2 = 29/16, simplified to 1 13/16.
On the Tape Measure
The mark at 1 13/16 inches (1.8125″) is a standard mark on all tapes.
Why 3 5/8″ Comes Up So Often
3 5/8″ is one of the most common measurements in residential framing. A standard 2×4 stud is 3.5″ wide — add a 1/8″ drywall reveal and you get 3 5/8″ as a finished wall dimension. This makes halving it a daily calculation on framing and trim jobs.
When You Need Half of 3 5/8″
1 13/16″ is the center mark for 3 5/8″ stock. Woodworkers use this to center drawer pulls on narrow face frames, find the midpoint of a door stop, split trim for mitered returns, and locate shelf pin columns in face-frame cabinets.
Finding 1 13/16″ on the Tape
1 13/16″ sits between the 1 3/4″ and 1 7/8″ marks — one small tick past 1 3/4″. On a tape showing 16ths it is the 29th mark from zero. Faster on site: find 1 3/4″ and count one tick toward 2″.