Half-Square Triangle
Specialty Ruler Cutting Guide
Half-square triangles are a versatile building block, and this page provides a yield reference for planning strip-cut HSTs using specialty rulers.
How Strip-Cut HST Rulers Work
Half-square triangles are one of the most versatile units in quilting, and many quilts call for a lot of them. If HSTs show up regularly in your work, a specialty HST ruler can be a worthwhile investment. While brands differ, these rulers all rely on the same underlying geometry—always follow the instructions that come with your specific ruler.
With strip-cut HST rulers, you begin with fabric strips cut to the same width as the unfinished HST size. Two strips are layered right sides together and cut at an angle, producing matched mirror-image triangles. Each cut yields a complete half-square triangle unit when the pair is sewn together, with no oversized cutting or trimming required.
This guide focuses on yield. It shows how many complete HST units can be cut from a single 42″ width-of-fabric strip at common strip widths, so you can determine how many strips to cut before you begin.
HST Yield by Strip Width (42” WOF)
This table shows how many complete half-square triangle units can be cut from a single 42″ width-of-fabric strip at common strip widths.
Note: When two fabric strips are layered right sides together and cut at the same time, each cut produces two mirror-image triangles. When sewn together, these form a complete half-square triangle unit without trimming or oversized cutting.