The Circle Savvy Ruler

Jen Wagner
Jun 26, 2023
3 min read

Updated: Jun 29, 2023

Discovering this ruler has made me soooo happy. It makes cutting out circles easy and accurate. And it is non-slip! If you don't like to use paper templates and are making any of my quilts that have circles such as Many Moons, Broken Moons, Fenced In, or Favorite Flavors then this ruler is for you! You can get it here in the shop! Let's talk about how it works....

But first, look at all that yummy non-slip texture on the back!

This ruler is made to cut quarter, half, and full circles in a lot of sizes. The size of each circle is measured by its diameter (shown in red). This increases in 1/2" increments from 3" to 15 1/2". So you can cut a 3" circle, a 3 1/2" circle, a 4" circle, a 4 1/2" circle, etc... up to 15 1/2".

How to use it:

The trick is to hold your rotary cutter so that the blade is upright, perpendicular to your cutting mat. Don't tip the blade to the side at all. The slots are big enough to use a 45mm rotary cutter when used this way. Plus you don't ever want to tip your blade when cutting because it will gouge your cutting mat. Cutting mats are only made to self heal from upright cutting.
Keep your blade against the inner edge of the slot to cut accurately.
When a pattern includes a paper template, you can tape it onto the ruler so it's easy to remember which slot to use. Tape it on top (not bottom) so that the ruler's non-slip texture is not covered up.
Look at the close up image of the ruler below. You'll see a fold line and a 1/4" seam allowance line on each side. Use these for lining up the edges of the fabric as I'll explain further in the next points.

To cut a quarter circle, start with a 90° corner on your desired fabric. Line up each raw edge of that corner on the 1/4" seam allowance lines. The 90° corner of the fabric will fit into the marked corner of the ruler. Then cut your desired size curve.
To cut a half circle, fold your fabric in half, so that the raw edge along one side is perpendicular to the fold, making a 90° corner. If your fabric does not have a straight edge, cut one first. Then put the raw edge on the 1/4" seam allowance line and the folded edge on the fold line. Then cut your desired curve.
To cut a full circle, fold your fabric in half, then in half again the other direction creating a 90° corner with a folded edge on each side. Then place that corner in the marked corner on the ruler so that the folds match the fold lines. Then cut your desired curve.

If you're piecing the quarter, half, or full circle you've cut out, you'll need to cut the curve into the frame (shown in red). Use the same method you used to cut the quarter, half, or full circle with the frame fabric, but use the slot on the ruler that is 1" smaller than the circle piece you already cut.
If you're making wedges, do so with the 22 1/2°, 45°, and 60° ruler marks with associated markings for the seam allowances.