Half of 3 9/16 inches is 1 25/32 inches (1.78125″, 45.24 mm).
How to Calculate It
Convert 3 9/16 to an improper fraction, divide by 2, then simplify. 3 9/16 = 57/16, divided by 2 = 57/32, simplified to 1 25/32.
On the Tape Measure
The mark at 1 25/32 inches (1.78125″) is a 1/32-inch mark found on many professional tapes. If your tape does not show 32nds, use the decimal 1.78125 with a digital caliper.
To find half of any tape measure measurement, enter it in TapeMath and tap the Half It button. The result appears instantly on the visual tape.