How to Cut Squares and Rectangles

Squares have four 90-degree angles (right angles) and four equal sides.True rectangles have four right angles and are twice as long as they are wide.Longer rectangles are sometimes called bars.

Cutting Tips

Keep patch angles accurate by carefully aligning the ruler line used to measure the width of the patch with the leading edge of the fabric. Choose any horizontal ruler line and align it to the bottom of the strip before cutting. When both a horizontal and vertical line match, you’ll have an accurate cut. Hundreds of specialty rulers are available for rotary cutting but you’ll do just fine with the basics. Add specialty rulers after you’ve become more accustomed to the technique and know which types of cuts you will make most often. You could also opt to purchase a cutting system. AccuQuilt is one company that makes cutters.  Remember all rotary cutting safety guidelines as you position fabrics to make cuts. Left-handed cutters must reverse fabric and ruler positions for many cuts.

How to Rotary Cut Half Square Triangles

Triangles have three angles and three sides, and that means at least one edge of every triangle is cut along the fabric’s stretchy bias. Handle triangles carefully to avoid stretching them out of shape. A good portion of the triangles you’ll use in your quilting projects are quick pieced, which means you won’t have to fool with stretchy bias edges, but there are times when it’s necessary to cut individual patches. Let’s start with half square triangles, one of the most commonly used quilting shapes. Half square triangles are used to make corner triangles for a quilt when quilt blocks are sewn on point. 

How to Cut Quarter Square Triangles

Quarter-square triangles look exactly like half square triangles, but they’re very different. The fabric’s straight grain runs parallel to the longest edge of a quarter-square triangle. The straight grain runs along the short edges of half square triangles. Quarter-square triangles are used in many quilt blocks, but we usually sew with quick-pieced units that eliminate the need for individual triangles. Quarter squares are also used as setting triangles along the sides of an on-point quilt. That configuration puts their sturdy straight grain edges on the perimeter of the quilt. Using half square triangles in the outermost position would result in a quilt with stretchy bias edges on its perimeter, not a good thing since you want quilt edges to stay as stretch-free as possible.

How to Rotary Cut Long Triangles

Scalene triangles have three unequal sides. The scalene triangle we use most often in quilting is the right scalene triangle, commonly called a long triangle. To cut patchwork that’s twice as long as it is wide:

How to Cut Long Triangles From Bars

How to Cut Equilateral Triangles

Equilateral triangles are the same length on each side, with 60-degree angles at each of their three corners. They are used in many quilts, including the traditional 1000 Pyramids design.

How to Cut Diamond Shapes

A diamond is basically a squished square. It has four sides of equal length, but its corners are no longer at 90-degree angles. Quilt patterns commonly call for diamonds with 30-degree, 45-degree or 60-degree angles at their narrow points. All three types of diamonds are cut from strips of fabric that are 1/2" wider than the finished height of the diamond.