Halving a measurement is one of the most common calculations in woodworking — finding the center of a board, splitting a space in two, or centering a joint. With whole numbers it is simple. With fractions, the math is easy to get wrong.
The Manual Method
To halve a mixed number like 3 5/8″:
- Convert to an improper fraction: 3 5/8 = 29/8
- Divide by 2: 29/8 ÷ 2 = 29/16
- Convert back: 29/16 = 1 13/16
The answer is 1 13/16 inches. That is a mark that is hard to find without checking the math carefully.
Common Measurements Halved
| Measurement | Half | Decimal |
|---|---|---|
| 3 5/8″ | 1 13/16″ | 1.8125″ |
| 2 3/4″ | 1 3/8″ | 1.375″ |
| 11 1/4″ | 5 5/8″ | 5.625″ |
| 7/8″ | 7/16″ | 0.4375″ |
| 1 1/2″ | 3/4″ | 0.75″ |
Using the Half It Button
In TapeMath, type any measurement and tap Half It. The result appears instantly on the visual tape canvas. You can then tap Half It again to quarter the original measurement.
Workshop tip: Half of an odd 1/16-inch measurement gives a 1/32-inch result. If your tape doesn’t show 32nds, use the decimal from TapeMath and measure with a digital caliper.