1/2 inch is the longest mark on a standard tape measure. It appears as a blue tick between each inch mark. The decimal equivalent is 0.5 inches (12.7 mm).
On the Tape Measure
Count 1 marks of this size from the last full inch line to reach 1/2. On professional colour-coded tapes the blue marks are the second-tallest marks between the inch lines.
Conversion Reference
| Fraction | Decimal | Millimetres |
|---|---|---|
| 1/2″ | 0.5″ | 12.7 mm |
| Half of 1/2 | 0.25″ | 6.35 mm |
Common Woodworking Uses
Centering joints, halving boards, cabinet door gaps, standard dado widths. The 1/2 mark is common in: standard framing, finish carpentry trim fitting, and cabinet construction tolerances.
How to find it fast: On the TapeMath visual tape, hover over any mark to see its fraction, decimal, and mm immediately — no counting required.