Squaring Up a Block

One of important steps when making a quilt is making sure that your block is the correct size. This is especially true when your blocks are made from more than one piece of fabric.

If your blocks are not the correct size, you will end up with troubles matching up seams and trouble getting the quilt top to lay flat.

Four examples of squared blocks

How to square up a block depends on the block you are making and the seams that are involved in your block. 

The block I will be using as an example is a half square triangle. The ruler I use is a 6 1/2 inch square. I like that it has diagonal lines and that there is tick marks for the 1/2 inch measurements. I can use it on any block that is 6 1/2 inches and smaller. 

Example of ruler I use for squaring up blocks

These squares I want to be 4 1/2 inches square. 

I start by laying the ruler on the block to get a good idea of how much trimming I will need to do. 

I try to line up the diagonal line along the seam and look to see that the block extends beyond the 4 1/2 inch measurement on all sides. 

At this point I can hold down the ruler and use my rotary cutter to trim down the two exposed sides. 

Example of block that needs to be squared

Then I turn the block under the ruler to expose the two un-trimmed sides.  The two sides that are trimmed should line right up with the 4 1/2 inch marks and the diagonal line should once again be lined up on the seam. Once that is all lined up, trim the remaining exposed sides. 

This is what it should look like after it is all trimmed. The diagonal line is lined up and all sides match up to the 4 1/2 inch measurements.

Quilt block after it has been squared up

If you have a four patch block, you will need to divide the size you are trimming to in half, and line the block up at that measurement in the center. 

If you have a block that does not have any seams you do not need to worry about lining up a center line. 

With a collection of squared up blocks, your quilt will come together much smoother!

If you have questions about how to square up other blocks, please leave a comment for me below, or email me and I will be happy to help!

Have fun quilting!


  • HI Mike,
    I would start with figuring out where a center is, if there is one. Then decide on where you want the first side to line up. That will help you decide where the other sides should be. Getting one of the clear rulers so you can see through it and see what it will look like when it’s cut is great!

    Becky Smith
  • Hi -

    What is the best way to trim up a string block using 2 and 2.5 inch strips?



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