1/4 inch is the third-tallest mark on a standard tape measure. It appears as a green tick between each half-inch mark. The decimal equivalent is 0.25 inches (6.35 mm).
On the Tape Measure
Count 1 marks of this size from the last full inch line to reach 1/4. On professional colour-coded tapes the green marks are the third-tallest marks between the inch lines.
Conversion Reference
| Fraction | Decimal | Millimetres |
|---|---|---|
| 1/4″ | 0.25″ | 6.35 mm |
| Half of 1/4 | 0.125″ | 3.17 mm |
Common Woodworking Uses
Mortise widths, standard gap spacing, drawer slide clearance. The 1/4 mark is common in: standard framing, finish carpentry trim fitting, and cabinet construction tolerances.
Also works for recipe halving — the fraction math is the same. Half of 1/4 cup is 1/8 cup. Use the TapeMath calculator for any fraction arithmetic.
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.