Easy Formula for Resizing Quilt Blocks

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Resizing Quilt Blocks is Easier Than You Thought!

Math? Definitely not my strong suite. It doesn’t help that my high school math teacher was the football coach and my class full of players and cheerleaders spent more time discussing, yep,  football, than math. It wasn’t until I got to college and had to take remedial algebra in order to qualify for the required math classes for my degree that I realized how short changed I was in the math department. I had great instructors in college, worked hard and (eventually) did well, and managed to handle my stint as a part time bank teller with aplomb, but even so, math and I have never quite gotten along.

So when I started quilting I stuck to patterns that were sized as I wanted them to be, cringing at the thought of having to increase or decrease the size of quilt blocks. That’s why I was thrilled to find an excellent tutorial about increasing and reducing the size of quilt blocks. Surprisingly, it’s not that hard. And now that I know how, I can finally turn that great block into a mini quilt, as I’ve long wanted to do!

Check out these simple instructions.

All you need is an inexpensive calculator, a little bit of courage, and the phrase:

“Ya start with whatcha want, and ya divide it by whatcha got.”

Imagine a darling little appliqué that’s just perfect for your wall, but the 12″ block is too large. You decide you’d like to make it 10″ square. You take the 12″ pattern to a photocopier with the intent to make it smaller, but what percentage should you make it? In the words of my friend, “Ya start with whatcha want, and ya divide it by whatcha got.”

Begin with your goal—it’s the reason you have to deal with quilt math in the first place. What you want is a 10″ block, so punch “10” into your calculator first. Hit the division key, then enter the number “ya got,” which is 12. Press the “=” key. The number 0.83333333333 pops up.

The copy machine wants a percentage, so move that pesky decimal point to the right by two spots, and then you’re done. Because this is a quilt, not a suspension bridge, you don’t need all of the decimal points, so ignore them. You need to reduce the 12″ pattern to 83.3% to make a 10″ block. Yes, it’s that easy to figure out.

change quilt block size

Let’s work it the other way and make it a little more complex. You have an appliqué pattern for a 6″ x 7 1/2″ heart, and you decide you’d like to make it at least 8″ wide, but you’re clueless how tall that will be. Ask yourself, what is it you want? An 8″-wide block. What do you have? A 6″-wide block. 8 ÷ 6 = 1.3333. This is what I call the “proportion number.” Move the decimal point two places to the right, and you’ve successfully determined you need to enlarge the heart pattern 133.3%. How tall will it be? In this case you multiply the original height (7 1/2″) by the proportion number, which is 1.3333. So, 7.5 x 1.333 = 9.99975. The heart will be about 10″ tall.

enlarge a quilt block

One way to check that you did the math correctly is to remember the following. The proportion number will always be greater than 1.000 if you’re enlarging something, and will always be less than 0.999 if you want to make something smaller. Always.

There are a few other tricks as well. The most important is to always remember to add the correct seam allowances.

Read the full article here for complete instructions.