How to Resize a Quilt Block

Kimberlee Tanner

How to Resize a Quilt Block

Every once in a while, we fall in love with a block and want to be able to make it in all sorts of different sizes! This week, we are breaking down the steps you’ll need to take in order to resize blocks up, down, or sideways. Okay, maybe not sideways.

The first thing to keep in mind, is we do not want to change the size of the 1/4″ seam. When dealing with square and rectangle pieces, before you change the size, subtract 1/2″ for the 1/4″ seam on both sides. Then we can determine what size the new piece needs to be.


Squares and Rectangles

To figure out the right size to cut your fabric, we need to go back to middle school math and proportions. With a simple ratio, we can resize a quilt block to whatever you would like.

If you are trying to make a block half the size of the original, you simply need to take the original measurement (after you’ve subtracted the 1/2″) and divide by 2. Halving a block is probably the easiest size adjustment to make. Likewise, if you want to go bigger by double, simple mulitply each measurement by 2.

For example: Original block is 18″ square. It is a 9 patch and each square is cut at 6 1/2″. You want to make the block 9″ finished.

  1. Remove the 1/2″ seam allowance, leaving you with a 6″ square.
  2. Divide the 6 by 2 for 3″
  3. Add back the seam allowance and cut your square at 3 1/2″.

Where things get a little more complicated (only a little though, don’t worry), is when you want to make the block a new size that isn’t simply half or a third of the original. If you want to take that original block of 18″ square and have a finished block of 12″, you can’t just divide by 2. This is where proportions come in to place.

First, set up your ratio. Put the size of the finished block on top, and the size you want it to be on bottom, for example: 18/12 (you can also reduce this to 3/2 for easier multiplication). You will use this same ratio for each step of the block. Going back to our previous example:

  1. Remove the 1/2″ seam allowance, leaving you with a 6″ square.
  2. Create the ratio. You’ll want to put the size of the current measurement on top, with an x on the bottom: 6/x
  3. Set up the proportion: 6/x = 3/2
  4. Cross multiply: 3x = 12
  5. Solve for x: x = 4
  6. Add back the seam allowance and cut your square at 4 1/2″.

This same method will work for any rectangular (and square) pieces. You can go larger or smaller to any size. Keep in mind, if you are doing a 4 patch, it’s going to be easiest to keep the blocks divisible by 2 (for 4, 6, 8, 10, etc). If it’s a 9 patch, I recommend keeping your finished blocks divisible by 3 (3, 6, 9, 12, etc). This will help eliminate weird measurements like 3 1/3″ finished squares.

Multi Step Squares

If you have a part of a block that is not rectangular or requires multiple steps, it gets a little trickier.

First, determine what size the section needs to be. Using the quarter square triangle example in our original block and halving it, the finished section needs to be 3″ finished. If we take the original pieces of 7 1/2″, subtract the seam and cut in half, we’d be starting with a 3 1/2″ block. Since we have two seams to sew, this likely won’t be big enough. Instead we are going to work backwards. A general rule we follow, is adding 1/2″ for each seam in the block. If you want to make sure to have lots of room for trimming, you could use 3/4″. Since there are 2 seams in the quarter square triangle, we will take the 3″ finished size, add 1″ for the two seams, and then add the 1/2″ seam allowance back in. This gives us a 4 1/2″ cutting size for each part of the quarter square triangle. You will likely need to trim it afterwards to get the final 3 1/2″.

Being able to resize quilt blocks can come in handy if you want to use a block in a different way than the original pattern shows. You can make them into pillows, table runners, place mats, wall hangings, and more. Don’t be scared to mix things up and make the quilt block work for you.

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