Monday, October 13, 2014

How to Resize a Quilt Block

My quilt guild (Ithaca Modern Quilt Guild) is in the middle of a scrap bag/block exchange. Everyone makes up multiple bags of scraps and exchanges it with someone else and they each make the other person a 12 1/2" x 12 1/2" (unfinished) modern block in return. I exchanged with 6 other members, so I have 6 blocks to make. I thought it would be fun to make some of the blocks for Tula Pink's book 100 Modern Quilt Blocks.

This is a wonderful book with lovely modern blocks. The only problem is that they are 6" finished (6 1/2" unfinished) blocks. A bit too small for me. Sew, I needed to resize the blocks to 12 1/2"x 12 1/2" unfinished block (12" x 12" finished).

WARNING: Math ahead!!!!

Block No. 16 from 100 Modern Blocks. The penciled in numbers are the new sizes for each block component to
make it 12" 12"

This is the formula for resizing any block, making it smaller or larger!

Desired Finished Block Size/Current Finished Block Pattern Size =  Block Multiplier

Example to convert the above block:

Desired Finished block size = 12"
Current Finished block pattern size = 6"

12/6 = 2
Block Multiplier = 2

This is the part that stumps most people, you have to remove the seam allowances on each component of the block because the seam allowance never increases or decreases with a pattern. It is always 1/2" (1/4" on each side).

The first component of the block is 1"x 3 1/2" for the 6" block pattern

1"(dimension) - 1/2" (both seams allowances) = 1/2"
1/2" x 2 (block multiplier) = 1"
add back the 1/2" seam allowance = 1 1/2"

3 1/2" (dimension)- 1/2" (both seam allowances in this dimension) = 3"
3" x 2 = 6"
add back the 1/2" seam allowance = 6 1/2"

The new dimensions for the first piece of this block  = 1 1/2" x 6 1/2"

You will need to do that for each of the pieces of the block.

If you want the whole formula:
((block multiplier) x (current component size dimension - 1/2")) + 1/2"

This block now measures 12 1/2" x 12 1/2"

This also works to make a block smaller.

Example: You would like to make a 12" x 12" finished current pattern sized block into a 9" x 9" desired finished block size.

9/12 = .75 would be your block multiplier. Use the same formula above to convert all of the pieces of the block.

I hope this helps! Let me know if you have any questions!

Today I'm linking up with Anything Goes Monday at Stitch by Stitch and with Design Wall Monday at Patchwork Times

Color Me Quilty!



  1. Thank you! This will be very helpful! I appreciate you taking the time to explain this. I've tried to resize blocks before but it didn't always work out so well. Dawn

  2. I will definately come back here (bookmarked you!) and figure this out. I will be nice to be able to alter the size of a block. Followed you from Anything Goes Monday linky

  3. A nice, logical explanation of how to do it!

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  5. Your method works ONLY with resizing squares and rectangles! If you are resizing triangle the seam allowances are different. For example, if you are resizing a piece that is cut on the diagonal, you need to subtract/add 7/8 of an inch (.875). By the same token, if you are resizing a piece that is cut on the diagonals both ways, you have to subtract/add 1 1/4 inch (1.25) for the seam allowances. I hope that's clear!

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