Bloc Loc HST Ruler

Featured Tool: Bloc Loc Half Square Triangle Ruler by Bloc Loc

Bloc Loc HST

What is this typically used for?

Squaring up half-square triangles (HST) to the correct size.

What was your first impression of the Bloc Loc Half Square Triangle Ruler?

I was intrigued by the idea of a specialized ruler for HSTs.

How did you use it?

I started by using it to square up half-square triangles in a mini quilt. I was impressed how well it helped me keep the diagonal seam exactly in the corner which is important for precise piecing and points.

How long did it take you to learn how to use it?

Not long at all. It was easy to learn and get in a rhythm of cutting.

What did you like best?

The way it helped keep the diagonal seam exactly in the corner. The markings are clear and easy to read. I make my HSTs 1/8″ larger than the math requires; it helps square-up precisely to the unfinished size for piecing. You can make various size HSTs with one ruler (in 1/2″ increments).

What did you like the least?

I bought the 6-1/2″ Bloc Loc first, knowing I could trim many sizes of HSTS 6-1/2″ square and smaller. I wish I had bought the set of 3 because I prefer to use the size closest to the size of HST – I have them all now!

Why do you NEED it?

Precisely trimmed HSTs enable a quilter to maintain sharp points and straight diagonal lines between blocks – Bloc Loc does a great job helping me accomplish that. HSTs are in so many quilt designs.

Could you see another potential use for the tool?

Mainly for squaring-up HSTs but I do that a lot! It is now my favorite way of trimming HSTs.

Who would appreciate the Bloc Loc Half Square Triangle Ruler most?

These are perfect for:

  • Beginner, intermediate, and expert quilters
  • Any quilter who is intimidated by half-square triangles


  1. Karen W. - October 4, 2016

    I just received my 2 1/2, 6 1/2, and 8 1/2 inch set of Bloc Loc Half Square Triangle Rulers and I can’t wait to use them. I’ve always had an issue with the traditional rulers rocking or slipping just enough to mess up the block.

    • Hayley - October 5, 2016

      That’s so exciting, Karen! We would love to hear how they work for you and to see your project when it’s finished.

  2. Kathleen - October 7, 2016

    Oh this ruler is awesome!! I recently purchased it from CT and am using it now for a baby quilt I’m working on. I am so glad I have it for this job. I bought the 6 1/2 inch one and I’m working with 4 1/2 inch HSTs.

  3. aLLISON - October 10, 2016

    i love these rulers – great tools!!

  4. Laurie Hood - October 31, 2016

    This is a great tool, Makes squaring up so perfect. Would recommend it for anyone

  5. Sylvia Loeding - January 12, 2019

    I have the 4 1/2 it is a great ruler