All-In-One Quarter Square Triangle Calculator
Notes: All measurements rounded up to next ¼". All yardage rounded up to next ⅛ yard.
| Color | 2-Color QST |
3-Color QST |
4-Color QST |
|---|
How to Make Quarter Square Triangles: A Complete Step-by-Step Tutorial (2-Color, 3-Color & 4-Color)
Quarter Square Triangles (QSTs) are one of those foundational quilt blocks that open up a whole world of design possibilities. Whether you know them as hourglasses, pinwheels, or simply QSTs, these versatile units show up in countless modern and traditional quilt patterns—and once you know how to make them efficiently, you'll find yourself reaching for them again and again.
In this tutorial, I'm walking you through three versions of the QST block: the classic 2-color (also called an hourglass block), a 3-color variation for added visual interest, and a bold 4-color version that brings all the scrappy, saturated energy. Each method builds on the same foundational technique, so if you're a beginner, start with the 2-color and work your way up. If you're already comfortable with Half Square Triangles (HSTs), you'll find that QSTs are a natural next step.
Before we dive in, here are a few quick definitions to keep handy as you follow along:
- QST – Quarter Square Triangle
- HST – Half Square Triangle
- RST – Right Sides Together (fabric faces touching)
A scant ¼" seam allowance is used throughout—that means just a thread or two shy of a full quarter inch, which helps account for the bulk lost when pressing seams.
Let's get into it!
2-Color Quarter Square Triangle (The Hourglass Block)
The 2-color QST, often called the hourglass block, is the most beginner-friendly version and a great place to start. You'll be working with just two fabrics, and this method is efficient—each pair of squares yields two finished QST units.
What you'll need: One square of Color 1 and one square of Color 2, both cut to the same size.
Step 1: Layer your Color 1 and Color 2 squares together with right sides facing (RST). On the wrong side of one square, draw a diagonal line from corner to corner. Sew a scant ¼" seam on each side of that drawn line, then cut directly on the line. Press your seams. You now have two Half Square Triangle units.
Step 2: Take one of your HST units and flip it to the wrong side. Draw a new diagonal line from corner to corner, this time crossing directly over the seam you just pressed.
Step 3: Align your two HST units with right sides together, nesting the seams so the colored triangles are in opposite corners—this is what creates that classic hourglass shape.
Step 4: Sew a scant ¼" seam on both sides of the drawn diagonal line, just as you did in Step 1.
Step 5: Cut apart on the drawn line, press your seams open or to one side, and trim each unit to your unfinished block size. You now have two identical hourglass QST blocks!
Working with directional fabric? If your background fabric has a directional print, cut your squares on the drawn 45-degree angle first to yield four individual triangles. Then mix and match those triangles to build your HSTs before continuing with Steps 3–5. This small adjustment ensures your print runs the right direction in every unit—no wasted fabric, no awkward angles.
3-Color Quarter Square Triangle
Ready to add a little more complexity and color? The 3-color QST introduces a third fabric into the mix, creating a block with more movement and visual contrast. This method yields four QST units from just a few squares, making it wonderfully efficient for building up yardage in a scrappy quilt.
What you'll need: Two squares of Color 3, one square of Color 1, and one square of Color 2.
Step 1: Gather all your squares and set the two Color 3 squares aside for now. You'll start by working with Color 1 and Color 2.
Step 2: On the wrong side of the Color 1 square, draw a diagonal line from corner to corner.
Step 3: Place the Color 1 square directly on top of the Color 2 square, right sides together (RST).
Step 4: Sew a scant ¼" seam on both sides of the drawn diagonal line, then cut on the line to create two HST units. Do not trim yet—you'll need the full size for the next step. Press your seams toward the darker fabric.
Step 5: On the wrong side of each newly created HST, draw a new diagonal line from corner to corner, running through the center seam.
Step 6: Place one Color 1/Color 2 HST on top of a Color 3 square, right sides together.
Step 7: Sew a scant ¼" seam on both sides of the drawn line, then cut on the line. This gives you two QST units per Color 3 square—and since you have two Color 3 squares, you'll end up with four QST units total.
Step 8: Trim each unit to your unfinished block size and press. Your 3-color QSTs are ready to sew into your quilt!
4-Color Quarter Square Triangle
The 4-color QST is where things really get exciting. Each quadrant of the block is a different fabric, giving you a bold, graphic result that works beautifully in both modern quilt patterns and scrappy layouts. The technique is similar to what you've already learned, just carried one step further.
What you'll need: One square of each of your four colors (Color 1, Color 2, Color 3, and Color 4).
Step 1: Gather one square of each color. On the wrong side of both the Color 1 square and the Color 3 square, draw a diagonal line from corner to corner.
Step 2: Place Color 1 RST on top of Color 2. In a separate pair, place Color 3 RST on top of Color 4. Working both pairs simultaneously keeps the process efficient.
Step 3: Sew a scant ¼" seam on both sides of the drawn diagonal line on each pair. Cut on the drawn lines, creating two HST units from each color combination. Press seams toward Color 1 and Color 3 respectively.
Step 4: On the wrong side of one Color 1/Color 2 HST, draw a new diagonal line from corner to corner, crossing through the center seam.
Step 5: Place the Color 1/Color 2 HST on top of a Color 3/Color 4 HST with right sides together, carefully nesting the seams so they lock into place. This step is key—well-nested seams mean crisp, accurate points in your finished block.
Step 6: Sew a scant ¼" seam on both sides of the drawn diagonal line, then cut on the line. Repeat this step with the second set of HSTs. You'll end up with four 4-color QST units total.
Step 7: Press all seams and trim each block to your unfinished block size. Step back and admire all four quadrants!
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